Thursday, May 31, 2018

Finding Gold Nuggets

Looking for gold in old, abandoned, mining districts - the old prospectors left a lot of gold along
in the abandoned mines and also missed many deposits along structural trends.
Gold nuggets have always attracted the interest of prospectors since the first recorded gold discovery in the US in North Carolina in 1799, when nuggets were found on Little Meadow Creek at what later became known as the Reed gold mine. The largest reported nugget from this area weighed 247.6 troy ounces. Little Meadow Creek produced so many nuggets that it became known as ‘the potato patch’ in reference to the large nuggets.

Not long after gold was found in North Carolina, gold was discovered in Georgia. A rush to Dahlonega, Georgia, in 1829 resulted in discovery of 500 gold placers and mines. Nuggets of 54, 42, 40, 35, 26, 25, 19, 18, 15, 11, 6, 5, 4, 3 and 2 troy ounces being recovered in Gilmer, Habersham, White, Cherokee and Lumpkin Counties.

Gold nuggets from Julian Creek, Alaska
The largest gold nugget found in Alaska was discovered in 1998 in Swift Creek near Ruby in central Alaska. The softball-size nugget, known as the Centennial nugget, weighed 294.1 troy ounces. Another large nugget recovered on Long Creek near Ruby weighed 46 ounces. Large nuggets (182, 107, 97, 95 and 84-troy ounces) were also found on Anvil Creek near Nome, western Alaska. In northern Alaska, nuggets of 146, 137, 61, and 55-troy-ounces were recovered in the Hammond River in the Brooks Range near Wiseman. In the same region, a 42-ounce nugget was recovered in Nolan Creek in 1994. The Gaines Nugget (122-troy-ounces), was found in the Kuskokwim Mountains of southwestern Alaska near McGrath in 1985 and several nuggets weighing up to 11 ounces, were recovered on Julian Creek in the Kuskokwim in 1988. Another large nugget (the Chicken Nugget) was found in 1983 on Wade Creek near Chicken in eastern Alaska that weighed 56.75-troy-ounces. And a nugget of 56-ounces was found on Dome Creek near Tolovana in central Alaska with a 52-ounce nugget was found on Lucky Gulch (Valdez Creek) near Denali in central Alaska.

Large nuggets recovered from Montana at California Gulch near Phillipsburg in the southwestern part of the state include a football-size nugget that weighed 612.5-troy ounces was recovered from California Gulch in 1902. This was followed by discovery of a 77-troy-ounce nugget from the same gulch. The largest nugget found in Colorado weighed 160-troy-ounces. The nugget was discovered Farncomb Hill at the head of the French Gulch placer near Breckenridge in 1887.

The largest nuggets in the US are from California. At Carson Hill in Calaveras County, a nugget weighing 2,340-troy ounces was recovered in 1854: it is also the largest found in the US. Another water worn nugget of 648-troy ounces was found at Magalia, California in 1859. These were too large to transport any distance in a stream and likely eroded from a proximal vein.

Fragile gold nugget attached to rounded pebble recovered from Snow
Gulch at Donlin Creek, Alaska
But it is hard to compete with Australia when it comes to nuggets. Some giant Australian nuggets include the Welcome Stranger of 2,217-ounces found in 1858 at Bakery Hill in Victoria. The Welcome Stranger was found near the town of Moliagul in Victoria in eluvium, and reported by some sources to have weighed 2,316-troy ounces. Other sources indicate the nugget weighed 2,380-ounces and 2,284 ounces. No matter what it weight, it was a very large piece of gold.

A 286 kg or 9,195-troy ounce nugget (this weight was the combined weight of the gold and quartz) was enclosed in quartz matrix and mined from a vein in the Star of Hope mine and was the size of a man. It became known as the Holterman nugget. This giant nugget was discovered in 1872 near Hill End on the side of Hawkins Hill in New South Wales, Australia. The amount of gold in this gold-quartz nugget was suggested to be 3,000 to 5,000 troy ounces.

A few months later, a larger gold mass was found in the same mine and had an estimated content of 5,000 ounces. However, this mass was broken up underground so that it could be more easily recovered. The Hawkins Hill gold deposits are very rich and yield considerable gold in Nuggety Gully adjacent to the lode (Hausel and Hausel, 2011).

Nuggets found in Arizona are small compared to Alaska and California and possibly is due to the lack of active streams in Arizona. But, there are placers known for nuggets including Arizona’s ‘Potato Patch’ at Rich Hill in the Weaver Mountains northwest of Phoenix. Another area known for nuggets is Greaterville south of Tucson in the Santa Rita Mountains. Nuggets in the Greaterville placers include one of 37 ounces. In the Weaver Mountains, samples of quartz with visible gold are found. Nuggets are also reported in the Bradshaw Mountains and in placers along Lynx Creek, French Creek, Big Bug Creek, the upper Hassayampa River, the Groom placers, and at Black Canyon (Hausel, 2019 - in preparation).

Gold from Rock Creek, Wyoming

Saturday, July 23, 2016

Gold Prospecting

Note visible gold (distinct yellow) surrounded by pyrite (brassy to silver 
metallic material). Core from the Copper King gold-copper mine, Wyoming.
My latest book 'Gold in Arizona' is now available. It is amazing how many gold deposits there are in Arizona, many sitting idle and many possible extensions of known gold deposits that have been overlooked. Every time I research gold deposits, I am so impressed by how many possibilities there are out there - hundreds and hundreds! My suggestion for those who are new at prospecting (or even been around for many years) is to start looking in known gold mining districts. Those old miners went for the obvious deposits and left a lot of good stuff. Just follow veins and gossans along trend and look for extensions.

Looking to find gold? You've come to the right place. After finding many gold anomalies over the years, mapping gold districts and gold mines, found I was able to identify some gold deposits including a major gold district that was described by one newspaper as having commercial gold mineralization, and also finding a world-class gold deposit with 6 other geologists, I decided to share my experience with prospectors! This latter deposit, known as the Donlin Creek gold deposit in Alaska, is one of the 10 largest gold deposits ever found in all of human history! We were even awarded recognition by the largest gold prospecting and mining association in the world - the Canadian PDAC for our discovery in 1988!

Remember those guys on Gold Rush? Yes, they were finding a lot of gold - a hundred ounces, a thousand ounces, a couple of tiny diamonds. We found more than 40 million ounces of gold, and also a couple of diamond deposits and even some world-class gemstone deposits - but - unlike the Gold Rush guys, I didn't get to keep any of my diamonds or gold - because of who I worked for. Yes, unlike the Fauci CDC gang, I worked for that part of government which thought it was unethical and a conflict of interest to take out patents and rake in $Billions after being paid by tax payers. And there is a good reason for this - imagine, getting all that money after you spread a virus around the world! But am I angry - heck no - I knew what I was getting into. Besides, I received a priceless education and if I had all those $billions, what would I do? Well, I would buy a 4-wheel drive truck with air conditioning, a nice AR-15 rifle, a small cabin in the mountains, and then I would give the rest to charity.

Gold in Arizona - A book about gold deposits in Arizona and where to find them.
Anyway, after hunting gold for more than 30 years, finding the yellow metal for mining companies and the State of Wyoming, I've decided to let you know about gold and other valuable treasures so, I've put together ideas on where to find gold. I published books on gold, diamonds, gemstones that will take you right to the source using GPS coordinates. Over the years I published hundreds of papers along with the books and currently, I'm working on another book on Gold in Arizona where there are a lot of very interesting gold deposits - so please watch for my new book on Arizona when it comes out on Amazon in 2017.

Rock foliation in the Archean age Miners Delight formation metagreywacke
along Rock Creek in the South Pass greenstone belt, provide excellent
natural riffles to trap gold where they crosscut the Rock Creek placer.
One of the state's I did a lot of work in was Wyoming. Wyoming is a strange anomaly. It should be filled with gold based on its geology - it has a continental core known as a craton with some greenstone belts and the craton has been partially destroyed by a very, active igneous system known as the Yellowstone Caldera. This region should be dripping in gold. Greenstone belts are well known in places like Canada and Australia for all of the gold they produce - so why not Wyoming? And the Absaroka volcanics surrounding the Yellowstone caldera contains all kinds of volcanic rocks that should also have gold - where has it gone? There are some scattered gold deposits in the greenstone belts in Wyoming, some large paleoplacer gold deposits, and a few porphyry copper deposits and gold deposits in the Absaroka Mountains, but little gold has ever been reported in Yellowstone. I would bet that Yellowstone is filled with gold, but it is illegal to prospect for gold in that region. Wyoming should have a lot of gold but it historically produced 50 to 200 times less gold than all of its surrounding neighbors (except Nebraska), yet it has more favorable geology for gold. This suggests there are still some major gold deposits that are hidden in Wyoming.

Take for instance the Copper King, the Carissa, the Wolf, Rattlesnake Hills, Seminoe Mountains, Ferris-Haggarty, Puzzler Hill, Kurtz-Chatterton, Mineral Hill, Black Buttes, Bear Lodge Mountains, Dickie Springs-Oregon Buttes and the copper porphyries in the Absaroka mountains. These areas all contain some gold and likely hide a few million+ ounce gold deposits. But why would Wyoming try to keep these deposits from you and me? I have some ideas, but I will let you come to your own conclusions. Other places I have been looking for gold include Alaska, Arizona, Australia, California, Colorado, Idaho, Montana, South Dakota. 

Gold in milky quartz vein material made as inlay in this match
box apparently owned by the Lost Dutchman. 
Some prospectors look for gold and find nothing, others find a little gold or other treasure: maybe ruby, sapphire, gem garnet, diamond, platinum, chromian diopside, palladium or some other valuable metal or mineral. I found all of these in Wyoming; and while prospecting for diamonds in California my gold pan touched some gold, chromian diopside, sapphire and a beautiful sapphire look alike known as benitoite. Diamonds were also found in gold placers in California by others (Hausel, 1998). Others catch a incurable case of 'gold fever' or 'diamond fever' such that they will give up everything - their homes, jobs and common sense just to search for gold. Some are so taken by the fever that they are exposed to scams and con-men who take whatever worldly possessions are left. 

If you want to get rich - learn a little about gold prospecting, geology from a good prospector or field geologist, and learn something about contracts and marketing. Personally, I found $billions in mineral deposits, but unfortunately, didn't learn anything about contracts or marketing - so yes, I never made anything more than wages and all of the minerals I could carry in my back pack. But I had a great time in the wilds.

There are many types of gold deposits to a geologist - hydrothermal, mesothermal, epithermal, replacement, etc., but to prospectors, there are only two types: placer and lode (Hausel, 2001, 2010). Famous placer deposits include Nome and Flat, Alaska, and Alder Gulch, Montana. Examples of lode deposits include the Mother Lode, California and the great Homestake mine in South Dakota.

There is not always a clear distinction between lode and placer gold deposits. For instance, the great Witwatersrand gold deposits in South Africa, the most productive in the world, are classified geologically as paleoplacers. Because they occur in brittle, consolidated rock (mined to depths of greater than 13,000 feet), most prospectors would consider these to be lode deposits. However, geologists classify the great Rand deposits as fossil (paleo) placers, since the gold was deposited in streams and rivers more than 2.5 billion years ago and now the rocks deposited by the former rivers and streams are preserved as hard, consolidated rock ledges.

Eluvial gold typically sits on top of a vein or lode. Eluvial deposits are restricted in size but may be enriched in gold. A
lode may not be exposed at the surface, but if you are finding gold-bearing quartz in alluvium, a vein is likely hidden 
under the alluvial (eluvial) cover. Such deposits are common in Arizona, though few of the eluvial-alluvial deposits have
been explored in detail in a search for the underlying lodes. In Wyoming, there are likely some giant gold deposits under
eluvium and alluvium near South Pass. 

Another not so clear distinction may arise with eluvial deposits. Eluvial deposits are essentially composed of detrital material weathered in place from a nearby (often underlying) source. Gold from an eluvial deposit would show little or no evidence of transportation. Since eluvial deposits are unconsolidated, some prospectors would consider them placers, even though they may directly overlie a lode. There are many examples of eluvial gold in Arizona. The arid environment is favorable for eluvial deposits due to the lack of active streams and - where there is eluvial gold, there is lode gold in the immediate area - something every prospector needs to keep in mind. Eluvial means that the material essentially eroded in place or from a nearby source area. In Arizona, there are many placer, alluvial and eluvial gold occurrences in streams, conglomerates and fanglomerates.

Paleoplacer gold, uranium and diamond deposit from the Snowy Range in
the Medicine Bow Mountains, Wyoming. Note the rock is very hard and
massive, yet it contains many rounded pebbles deposited in streams more
than 2 billion years ago. Uranium, thorium, gold and even diamonds have
been recovered from these rocks in Wyoming. 
Placer deposits
Placers consist of detrital gold and other valuable minerals transported in streams or by wave action to be concentrated with other heavy minerals known as black sands. If you have ever panned for gold, you are familiar with black sands. Black sands consist of dark opaque minerals with greater than average specific gravity, which may include magnetite, pyroxene, amphibole, ilmenite, garnet, sphene, chromite and monazite, as well as some rare light-colored minerals with relatively high specific gravity such as cassiterite and scheelite. If you ever panned near Wilson Bar or Wilson Gulch at South Pass, Wyoming, you may have found all of this heavy, nagging, white to brown quartz that was impossible to pan out. Well, it probably wasn't quartz. With a shortwave ultraviolet light, this heavy quartz likely will fluoresce blue-white simply because it was not quartz, but instead is scheelite, a tungsten ore found in some of the gold ore at the Burr and Hidden Hand mines (Hausel, 2009). When found,on public land, placers can often be claimed under the 1872 mining law. But if you want the lode under the placer, you better look at filing a lode claim too.

Take a close look at this sample. It was one of many found by 
field trip attendees on my past field trips to South Pass. 
Everything you see that is gold colored in the rock is gold.
This was found at the Carissa mine. 
Other minerals of potential economic interest with relatively high specific gravity may occur in gold placers such as cassiterite, scheelite and a host of gemstones including ruby, sapphire, gem-garnet, diamond, platinum, and palladium. While prospecting for diamonds in the Laramie Mountains in southeastern Wyoming, several samples with trace amounts of ruby and sapphire were recovered along with heavy minerals (Hausel and others, 1988; Hausel, 1998). These were eroded from nearby, undiscovered, corundum (sapphire, ruby) mica schists and gneisses. How do you tell if you have ruby or sapphire in your gold pan? Look at crystal habit. The habit is the common form of the crystal. Ruby and sapphire form hexagonal crystals that are bounded by two pinacoids (basically flat surfaces).

While prospecting for diamonds in the Sierra Nevada of California, I found sapphires and benitoite near Poker Flat. And one prospector (Paul Boden) found a couple of excellent gem-quality octahedral diamonds while searching for gold on Cortez Creek in the Medicine Bow Mountains, Wyoming, and another prospector (Frank Yassai) found several diamonds in Rabbit Creek, Colorado while prospecting for gold.
Another sample collected on my field trips for the public. 
Visible gold is seen in every vug in the piece of quartz found
at the Carissa mine at South Pass. So what did the State do?
This likely multi-billion dollar gold deposit was purchased by
the State of Wyoming, withdrawn, and placed within the 
South Pass City historic site where the state now collects 
nothing for all of that gold. 

During erosion of bedrock, these heavy minerals mix with abundant light-colored, glassy, transparent to opaque minerals with low to average specific gravity such as quartz, apatite, feldspar, and mica. Along with these, minerals with high specific gravity are slowly moved in streams with moderate to high water velocity. The sediment carrying capacity of a stream diminishes with decreased velocity. The heavy minerals concentrate by settling out where diminished velocity occurs; such areas are marked by a distinct increase in black sands. Heavy minerals tend to concentrate at the bottom of a stream along the leading edge of stream meanders, behind obstructions (i.e., rocks, cracks in bedrock) and at waterfalls. Since many streams lack sufficient velocity to carry gold for any great distance, much of the gold in these streams (particularly where it is concentrated in pay streaks) is probably transported during flash flooding events or during heavy spring runoff.

The distances heavy minerals can be transported are not known with any accuracy. Some minerals can be transported great distances. For example, because diamond is 6000 to 8000 times harder than any other mineral and is not very heavy (specific gravity of 3.52 compared to 2.87 for quartz), there are cases where transport distances for diamonds has exceeded 600 miles. In southern Africa, diamonds are found in kimberlite pipes, in stream and river placers and in extremely rich beach placers along the west coast of the continent.

Such great transportation distances for gold are not possible. Gold is too heavy (specific gravity of 15 to 19.3), so when found in streams it is thought to have been derived from a nearby source. In some unusual cases, gold may be transported greater than normal distances while in solution. In Alaska, geologist Paul Graff identified gold that had crystallized in nuggets downstream from nearby lode deposits. Maximum transportation distances for gold in solution is unknown.

The color change (upper arrows) more than 1 foot above the gold pan (circled) mark the site of a pay streak in Smith Gulch discovered by prospectors Hank Hudspeth and Buddy Presgrove. This streak was produced during a flash flooding or unusually high spring runoff. A second pay streak was found at the base of the open cut near the standing water (lower arrow). Even though this placer was located in a dry drainage when mined, it was immediately down slope from several lode deposits that provided a favorable site for gold concentration. At this point, the prospectors had not yet reached bedrock, where there is likely another pay streak. 

Flash flooding events appear to be important in forming pay streaks of gold and diamonds. Pay streaks, or lenses of gold-enriched gravel, are often found in zones of coarser-grained pebbles and cobbles. The pay streaks may be scattered over one or more intervals in a vertical column of gravel.

Schematic showing development of meander. Where the stream starts to meander, water velocity decreases & minerals with higher specific gravity concentrate (stippled areas). Through time, the meander may mature, leaving deposits on the inside banks as the stream migrates. Material in the stream as well as the adjacent bank material (which may be high and dry after episodes of flooding and high water) will contain heavy minerals & possibly gold and diamond. 

Where meanders occur in streams, gold may concentrate on the inside of the initial curve in the channel, as well as in the bank (point bar) on the upstream part of the inner meander where gold was deposited in the past. As an example, one of my favorite places to take students in the past in my prospecting courses was near Bobbie Thompson adjacent to a historical gold placer in Douglas Creek, Wyoming. Here the bank gravel sits away from the active stream, but contains enough gold to keep the interest of the students.

Gold Road Lode vein in northwestern
In addition to modern placers, some regions contain paleoplacers. Places like Wyoming and the Witwatersrand of South Africa are famous for paleoplacers scattered over large regions. In the Witwatersrand, the paleoplacers are so important, that they have produced about 50% of all of the gold mined in human history. Today, they have the deepest mines on earth. In Wyoming, most paleoplacers have either not been prospected, or only have been cursory examined at best, even though it is a safe bet that economic gold deposits occurs in some of these. Paleoplacers are simply fossil placers that were deposited by streams or by wave action along prehistoric seas in the geologic past. In most cases, these may not lie anywhere near an active stream or sea today; thus, mining would either require transporting water to the paleoplacer, or transporting material from the paleoplacer to water.

Wayne Sutherland, WSGS geologist, examines paleoplacer at Dickie Springs to the south of South Pass. Note all of the rounded boulders and cobbles typically found in active streams and rivers. 

Where the paleoplacer consists of relatively unconsolidated gravel, it can be mined in a manner similar to a sand and gravel operation. If the operation is located near a road, the sand and gravel by-product can be used in road construction. Conversely, gold can be extracted as a by-product of sand and gravel operations. For example, gold was found in several sand and gravel operations and placers adjacent to Interstate 80 in southern Wyoming (Hausel and others, 1993). Where paleoplacers are extremely old and well consolidated, such as in the Witwatersrand, the gold is typically mined underground.
Gold recovered the dry paleoplacer near
Dickie Springs. The gold suggests a 
hidden lode somewhere between this site,
and the exposed South Pass greenstone belt 
to the north. Foster Howland with Hecla Mining
 explored this area & identified a good target - 
a sulfide-bearing iron formation at depth that
could contains gold. The project was 
terminated before the work was completed. 

In the South Pass greenstone belt in western Wyoming, giant paleoplacers surround the region at McGraw Flats to the north and Oregon Buttes-Dickie Springs to the south. And there are smaller ones in between. The southern paleoplacer was reported by Love and others (1978) of the US Geological Survey to contain more than 28.5 million ounces of gold, yet most of this area is unexplored. Along the northern flank of the Seminoe Mountains greenstone belt, the Miracle Mile paleoplacer is unexplored even though myself and field assistants recovered gold from the dry paleoplacers nearly everywhere we sampled. This paleoplacer was discovered by prospectors Charlie and Donna Kortes, also contains dozens of G10 pyrope garnets that indicate somewhere in this region is a very rich diamond deposit or deposits. Keep your eyes out for diamonds when looking in any placer or paleoplacer! Paleoplacers in the Medicine Bow and Sierra Madre Mountains in southern Wyoming yielded some gold and diamonds, but are rich in uranium and thorium.

Lode deposits
One might think of lode deposits as veins or other consolidated rocks that contain anomalously high quantities of metal (e.g., gold). Many lodes occur as distinct quartz veins. These may form linear to tabular masses of quartz within country rock. One important characteristic of many productive veins is the presence of sulfides, such as pyrite (fool’s gold) or arsenopyrite (arsenic-pyrite).

Classic lode. This auriferous quartz vein in metatonalite at the Mary Ellen
mine at South Pass was offset along a small, reverse fault. Lodes are considered
in situ deposits in hard rock
When pyrite oxidizes, it produces sulfuric acid and rust (a massive sulfide deposit of pyrite will smell like rotten eggs, and a massive arsenopyrite deposit will smell like garlic, and both can have considerable gold and silver), resulting in a gossan at the surface and a potential supergene zone (a mineral deposit, or enrichment, formed by descending fluids) a few tens of feet below the surface. Gossans are the oxidized sulfide-rich parts of veins and other mineral deposits that have a distinct, rusty appearance. These gossans offer excellent visual guides in the search for gold and other mineral deposits. In any historic mining district, you will often find dozens, if not hundreds, of old prospect pits dug into the rusty rocks. Prospectors learned to recognize gossans as guides to ore deposits.

Gossan at Red Mountain in the San Juan Mountains, 
southern Colorado. Note all of the red to light 
yellow-colored rock found nearly everywhere in the photo. 
These are gossans that contain significant amounts 
of gold and silver. 
Gossans are good places to search for high-grade gold in lodes. The recognition of gossans in the field can be very helpful to the prospector. For example, gossans produced from the leaching of pyrite are typically very rusty (reddish-brown) in appearance; gossans produced from arsenopyrite are typically greenish-yellow. Gossans are so important that an entire book was written on their different characteristics (Blanchard, 1968).

Large gossans that cover several acres may be situated over giant sulfide-enriched veins or massive sulfide deposits. These may contain gold and/or valuable base metals (copper, zinc, lead, etc). One very large gossan in the Hartville uplift in eastern Wyoming is so distinct that I ended up naming it “Gossan Hill”—it overlies a massive sulfide deposit. One of the better places to look for specimen-grade gold samples is within gossans containing boxworks. Boxworks is a distinct vuggy and rusty rock.

This specimen of boxworks exhibits pore spaces formed where sulfide minerals were removed by oxidation. The sulfides
 were oxidized by oxygen-rich water near the surface, leached out, and removed. Gold, which often is found in pyrite, is
mostly inert, and may remain in place within the boxwork pits, while some of the iron from the pyrite stains the rock and
the walls of the pits. Much of the sulfur was likely mobilized by groundwater cane carried down dip. At Bradley Peak in
the Seminoe Mountains, I found nearly a
dozen of these samples and started a gold rush in 1981. Even this area 
remains essentially unexplored to this day!

Some faults and associated breccias may also be mineralized. Breccias are zones of broken rock containing distinct angular rock clasts. When found, gold may occur in the matrix of the strongly limonite-stained gossan surrounding rock fragments. Other faults, known as shears, may also be mineralized. These shear zones consist of granulated rock. Within many shears, gold is often found associated with rust-stained quartz. Many shear zones, particularly those in greenstone belts, have been quite productive for gold. In some gold mining districts in the world, nearly every foot of the exposed shear zone has been prospected at the surface.

A breccia (angular fragments) cemented by quartz - a good place to check for gold. Such breccias are formed in faults or by the release of gas under pressure which produces a breccia pipe. Note the difference between the breccia with angular rock fragments (left) and the Tertiary-age (about 30 million years old) paleoplacer with rounded pebbles (below left) and the stretched pebble conglomerate (very old paleoplacer nearly 2 billion years old) (below right) All three can contain gold. 

Consolidated conglomerate 

Ore shoots
Many veins have sporadic gold values with localized ore shoots enriched in gold. Some of these shoots may be enriched 100 to 1000 times the average value of the vein. The challenge given the prospector is how to recognize these shoots. 

Ore shoots can be structurally or chemically controlled. Where pressures and/or temperatures dramatically dropped during hydrothermal mineralizing events, structurally controlled ore shoots occur. Chemically controlled ore shoots may occur where there was a chemical reaction between the mineralizing fluids and country rock. Any where an igneous rock (hot) comes in contact with a reactive rock (such as limestone) is a great place to find gold and other minerals.

Paleoplacer with stretched pebbles from the Medicine Bow Mountains, WY
These ancient stream deposits were later deformed under great pressure
that flattened and stretched the pebbles in the rock. Such rock sometimes
contain gold, uranium and even diamonds - basically any type of heavy
mineral that would have been carried in rivers more than 2.5 billion years
ago before the earth had any appreciable oxygen.
When searching for structurally controlled ore shoots, it is necessary to look for places where one would expect the pressure to have decreased along vein systems. Some structurally controlled ore shoots are found in folds. Many fold closures in gold-bearing veins will be enriched in gold. Another type of structurally controlled ore shoot includes vein intersections. Some intersections of gold-bearing veins have been dramatically enriched in gold.

The Carissa mine at South Pass. The shear zone in the background is rich in gold [average grade reported at 0.3 opt Au, much higher than the ore currently recovered from mines in Nevada (0.02 to 0.15 opt Au) (opt Au= ounces per ton of gold)]. Although not visible to the untrained eye, this giant gold-bearing structure lies in a large fold in the shear. The ore zone is 970 feet long, nearly 1,000 feet wide and continues to a minimum depth of 930 feet (and likely a few thousand feet deep). The property was withdrawn by the State of Wyoming even though it very likely hosts a few million ounces of gold worth a few $billion. 

There are many other types of structurally and chemically controlled ore shoots. For example, while prospecting in the Gold Hill district in the Medicine Bow Mountains of Wyoming, I noted gold was almost exclusively found in veins adjacent to amphibolite. The same veins in quartzite were unproductive. Additional information on ore shoots can be found in various books on economic geology and ore deposits (see Earll and others, 1976; Evans, 1980; and Peters, 1978).

What does gold look like?
Most people have a difficult time identifying gold at first. Gold is very heavy! It is 15 to 19 times heavier than water, it is malleable (it will easily scratch with a pocket knife), and has a distinct gold color that does not tarnish. Most people mistaken mica, pyrite (fool's gold), or chalcopyrite (copper-fool's gold) for real gold. These latter minerals are brittle and will crush to a fine greenish black powder. But don't be fooled. Some pyrite (fool's gold) may contain up to 30 parts per million gold hidden in the crystal structure (about an ounce per ton). To test for this gold, you will either have to assay, or powder the pyrite and pan it for gold. And chalcopyrite may have as much as 20 parts per million gold hidden in its crystal structure. 

Large specimen of mica (muscovite) shows a mirror-like surface, bronze-color, and will break into tiny pieces by a pocket knife unlike gold. Tiny mica flakes will easily move around in a gold pan while panning. As you pan, if the gold material stays flat on the surface of your pan and is difficult to move, it may be gold. However, if it moves easily, rotates or spins in the water, it is not gold. Mica is hard to pan out of a gold pan simply because it is essentially 2-dimensional and will cut through the water like a knife. 

Gold in the pan is angular, heavy and a brightly yellow-gold color. It does not have mirror-like surfaces and will stay put in the pan. Pyrite will crush to a greenish black powder and the same with chalcopyrite (photo of gold from Dickie Springs, Wyoming courtesy of Dr. J.D. Love). 

The search for productive gold deposits requires a good background in prospecting and economic geology as well as some luck. However, there are literally hundreds of occurrence and deposits in nearly every state in the West including Alaska. The best way to begin prospecting is to get a book that describes the gold mines and placers and visit these as I have found there are always many deposits near old gold mines that have been overlooked. This is how I found more than a hundred gold deposits and anomalies. An understanding of geology also helps: I found an entirely new gold district (Rattlesnake Hills in the early 1980s) that was missed by everyone else, simply because of the geology. It had very favorable geology and is currently being explored and drilled by several companies even though I discovered this district nearly 30 years ago! I was also on the discovery team of the giant Donlin Creek gold deposit in Alaska. Part of our discovery team (Rob Retherford, Bruce Hikock, Toni Hinderman) had recognized that some place gold at Donlin Creek was like corn flakes, very angular. Paul Graff visited the area with Mark Bronson and Richard Garnett and WestGold decided to explore this region. I was hired to map the deposit - it was a major discovery that includes more than $42 billion in gold! Yet this discovery occurred all the way back in 1988 and the gold deposit, considered one of the largest in the world, still is not being mined (but is under exploration).

So, get hold of books in your area that describe where gold deposits are found. Pick out the exciting areas and look at the deposit described in a book and look around for what the old prospectors missed (they missed a lot!). Search for publications at your local geological survey (usually they have a few good publications). If you are in Wyoming, I published numerous books that are available on the Internet, the University of Wyoming bookstore and the Wyoming Geological Survey. In particular, get copies of Bulletin 68 and 70 and Report of Investigations 44. If in Arizona, there are likely hundreds of lode gold deposits that have been missed because of so many eluvial placers with no reported gold source (the gold came from somewhere!). Colorado and California have hundreds of possibilities, but personally, I would look in Arizona, Wyoming, Montana and Alaska. For additional information on gold, gold in Nevada, New Mexico, Utah, Idaho, Washington, Oregon and South Dakota, watch for other blogs and keep track of my GOLD and Consulting websites as I will periodically update these. Myself and my son (Eric) who is also a geologist, are currently writing a couple of books on gold and we will tell you exactly where to look.

"Old mines never die, they are just forgotten". And enormous gossan exposed at the United Verde mine in Arizona. This property was mined for copper, gold, silver and zinc over many decades and then it was closed. Was it mined out? No - few mines are ever mined out. It is just that the economics prior to the 1960s made it uneconomic to mine. But at today's high gold prices (compare $1700+ per ounce to $35 per ounce) many of these old mines are likely economic. It is reported that the former miners did not recover the low-grade zinc and copper ore that likely contains more than a million ounces of gold. Additionally, after examining the aerial photos over this region, it is apparent that there is a 10+ mile gossan that likely is underlain by several massive sulfide deposits that remain unexplored. Remember, old mining districts often contain many opportunities. 

Fisher dredge on Rock Creek, South Pass, Wyoming showing unmined ground
While you are looking for gold deposits, remember, there are probably just as many if not more gemstone and diamond deposits that have been missed by prospectors and geologists. I recently found a major field of cryptovolcanic structures that are likely diamondiferous kimberlites sitting right along Interstate 80 west of the State Capitol of Wyoming. With a good arm, one could probably hit some of these with a rock next to the interstate. These remain unexplored and were just discovered a couple of years ago! 

Some of these are so obvious, that it makes one wonder what everyone has been doing. Take for instance the Cedar Ridge opal deposit. Probably the largest opal deposit in North America was sitting right on the side of the main highway to Riverton, Wyoming and exposed in numerous road cuts in an oil and gas field and in a pipeline - but totally overlooked. Even after the announcement of this major field in 2003, it still remains pretty much unexplored! This deposit contains opals in road cuts that weigh more than 100,000 carats and has common, fire and precious opal and some spectacular 'Sweetwater' agates. How anyone could have overlooked this, is beyond comprehension. But it sat there for several million years, untouched, other than a few brief mentions of the presence of opalized rock in old USGS reports! 

Then there is likely the two largest colored gemstone deposits on earth that I found at Grizzly Creek and Raggedtop Mountain in the Laramie Range. How these can remain essentially untouched is beyond my understanding. At one deposit, I found gem iolite as large as 24,000+ carats with pieces in the outcrop that likely weigh hundreds of thousands (if not millions) of carats. The other deposit may host as much as 2.7 trillion carats based on past geological reports (that missed the fact that these were gemstones). Just imagine how valuable these deposits are even if you mined them, cut the stones, sold them and only made $1 profit! The primary gemstone, iolite, can be cut for $0.5/carat and is sold for $15 to 150/carat. Nice profit! For those of you who wonder - I do not have claims on any of these, it was considered unethical when I was employed at the WGS (Although, today I am a consultant).

Stacked pay gravel on Rock Creek placer, South Pass.
Note the distinct clay and silt false bedrock layer. The
gold occurs in the gravels above and below the false
bedrock. The clay and silt represent a very dry period. 
There are many placer and lode deposits to be found, although the discovery of entirely new mining districts is rare. In all my years as an exploration geologist, I have only been able to find one new gold district. However, I have found many gold deposits within known districts and you should be able to do the same armed with a little knowledge.

Some of the better areas to search for gold are historical mining districts. In my experience, it is rare that any ore deposit has been completely mined out. Many historical and modern mines still contain workable mineral deposits as well as nearby deposits that have been overlooked. Many well-known giant mining companies of the past were notorious for overlooking significant ore deposits and ignoring others. For example, AMAX explored a large porphyry copper-silver-gold-lead-zinc deposit in the Absaroka Mountains southeast of Yellowstone. They focused on the prophyry and ignored nearby vein deposits that assayed >100 opt silver! Thus, one could potentially make a living just following up on the exploration projects of many of these past giants [as well as some projects of present giants]. 

Pyrite (fool's gold). Note the brassy color (not gold colored). 
Pyrite is brittle and the upper photo shows crystalline (cubic) 
pyrite. Upper specimen from the Lost Muffler gold prospect, 
Rattlesnake Hills and lower specimen from the Pickwick 
vein, Kirwin district, Wyoming. But don't throw them away: 
pyrite can contain a few hundred parts per million to potentially
2,000 ppm (64 ounces per ton) hidden in its crystal structure! 

Some References 
Blanchard, R., 1968, Interpretation of leached outcrops: Nevada Bureau of Mines Bulletin 66, 196 p. 
Earll, F.N., and others, 1976, Handbook for small mining enterprises: Montana Bureau of Mines and Geology Bulletin 99, 218 p. 
Evans, A.M., 1980, An introduction to ore geology: Elsevier, Amsterdam, The Netherlands, 231 p. 
Hausel, W.D., 1989, The Geology of Wyoming's Precious Metal Lode and Placer Deposits: Wyoming Geological Survey Bulletin 68, 248 p. 
Hausel, W.D., 1991, Economic Geology of the South Pass Granite-Greenstone Belt, Wind River Mountains, Western Wyoming.Geological Survey of Wyoming Report of Investigations 44, 129 p. 
Hausel, W.D., 1997, Copper, lead, zinc, molybdenum, and associated metal deposits of Wyoming: Wyoming State Geological Survey Bulletin 70, 229 p. 
Hausel, W.D., 1998, Diamonds and mantle source rocks in the Wyoming Craton, with a discussion of other U.S. occurrences: Wyoming State Geological Survey Report of Investigations 53, 93 p. 
Hausel, W.D., 2001, Placer and lode gold deposits: International California Mining Journal, v. 71, no. 2, p. 7-34. 
Hausel, W.D., 2009, Gems, Minerals and Rocks of Wyoming. A Guide for Rock Hounds, Prospectors & Collectors. Booksurge, 175 p. 
Hausel, W.D., 2010, How to find gold: Lost Treasure Magazine, July, p. 56-60. 
Hausel, W.D., Marlatt, G.G., Nielsen, E.L., and Gregory, R.W., 1993, Study of metals and precious stones in southern Wyoming: Wyoming State Geological Survey Mineral Report MR 93-1, 54 p. 
Hausel, W.D., Sutherland, W.M., and Gregory, E.B., 1988, Stream-sediment sample results in search of kimberlite intrusives in southeastern Wyoming: Wyoming State Geological Survey Open File Report 88-11, 11 p. (5 plates) (revised 1993). 
Hausel, W.D., and Sutherland, W.M., 2000, Gemstones and other unique minerals and rocks of Wyoming—A field guide for collectors: Wyoming State Geological Survey Bulletin 71, 268 p. 
Peters, W.C., 1978, Exploration and mining geology: John Wiley and Sons, New York, 696 p. 

Specimen of chalcopyrite in quartz (with green malachite and silver-colored specularite) from the Kurtz-Chatterton mine (a great, unexplored, gold prospect) from the Sierra Madre, Wyoming. The chalcopyrite is the brassy-orange material in the specimen. Some chalcopyrite can contain as much as 20 ppm Au (a considerable amount of gold equal to about 0.7 ounces per ton) hidden in the crystal structure along with some silver. 

Just hit a rock and you will smell garlic? No, it was not that Italian prospector standing up wind from you - it was most likely the smell of arsenic from the arsenopyrite that you just hit with your rock hammer. Arsenic-pyrite, or arsenopyrite, often is found around many gold or silver deposits and can hold up to 1,000 ppm gold (32 ounces per ton) hidden in its crystal structure. Whenever I find arsenopyrite, I have it assayed. Sometimes the mineral will assay high in silver, such as at South Pass. At Donlin Creek, Alaska, both arsenopyrite and stibnite yield high gold assays. Thus, arsenopyrite is a good guide to precious metals. The rock above contains considerable prismatic, silver gray metallic arsenopyrite with scorodite (reddish brown to yellow oxidized arsenopyrite). 

Cuprite (earthy red), malachite (green) and tenorite (black) from the Sunday Morning prospect, Seminoe Mountains, Wyoming. These minerals can all contain some silver and gold in their crystal structure. Malachite will emit CO2 bubbles just like soda pop when sprayed with dilute (10%) hydrochloric acid. Spray cuprite and tenorite with dilute hydrochloric acid and rub a well used rock hammer in the wet mineral and it will replace the worn parts of your hammer with native copper. 

Gold from Rock Creek at South Pass. 

Green malachite, a copper carbonate, often contains anomalous 
silver and gold detectable in assays 

Azurite (blue), tenorite (black) and cuprite (red) -
classical copper minerals. Don't make
the mistake many prospectors do - collect
these pretty minerals without having some assayed.
Copper minerals often contain gold hidden in the
mineral or replacing some copper atoms in the crystal
lattice. They also contain silver more often than not.

Not all assayers are created equal. Do some research and check on an assayer before using them. 

Friday, October 23, 2015

Rock Hounding and Prospecting

Emerald jade specimen with quartz crystals from Wyoming. To identify the quartz, first look at the crystal in the bottom
  center of the jade. Count how many crystal faces you see. There are 6, meaning it is hexagonal. Quartz is hexagonal and
 often white to transparent. Another clue comes from the crystal to the left and little above. It lies perpendicular to the first 
crystal and suggests the crystal has long prime capped by a pyramid - just like quartz. To verify that you have jade, you
 can test the hardness, but one of the only ways to verify is to have it x-rayed because we have no visible crystal structure
 (which is typical of jade). 
Rock Hounding Wyoming (modified and revised with permission from Planet News)
Wyoming was considered the poorest of all states for gemstones and rocks until recently - it even had a worse reputation than Florida and Louisiana for rock hunting - two states that have practically no rocks - just a lot of limestone, dirt and swamps – so what happened? It started in 1975. At the time, Jade was king. Impressive jade boulders were found near Jeffrey City in central Wyoming, but otherwise, nothing of note had been found in the Wyoming cow pastures other than a few agates, jasper, coal, oil, gas, bentonite and uranium. Then Dr. Mac McCallum and Chuck Mabarak from Colorado State University sampled a newly discovered kimberlite (diamond) pipe in Wyoming. A sample was sent to the US Geological Survey - Eureka! Several tiny microscopic diamonds were found by accident! McCallum went on to make a name for himself and became respected internationally as one of the top diamond researchers in the world - so what did Colorado State University do to this productive geologist - they gave him the boot. Politics! Dr. McCallum also brought to light that Wyoming had a major palladium and platinum deposit at the New Rambler west of Laramie. So, the seeds were planted and discoveries were made. But what CSU moron let this geologist go?

Panning for diamonds & gold
Wyoming never looked back after these discoveries. Then another geologist came on the scene. This geologist dreamed of treasure. Professor Dan Hausel with the Wyoming Geological Survey became known as a discoverer. For the next 30 years, he made new discoveries nearly every year! Imagine one person making new discoveries over 3 decades in a place where only the deer and the antelope roamed. We'll just refer to him as the Professor. He put Wyoming on the map!
Although olivine was known in the Leucite Hills for more than a century, no
one ever bothered to examine these gems. This photo shows both raw gems
and the faceted gems from the original discovery

One of two piles of more than 13,000 carats of gem peridot
recovered from just two anthills in the Leucite Hills) in 1997. 
People usually get the impression everything has been found. Not so! Discoveries were made in Wyoming every year from 1977 to 2007 because of the Professor. When he left Wyoming - the discoveries dried up - not a single discovery has been reported since 2007! But the Professor was not alone. Other geologists made discoveries including Ray Harris, Robert Houston, and J.D. Love!

Diamonds were accidentally discovered in 1975, and more than 40 diamond deposits (known as kimberlite pipes) were found along the Colorado-Wyoming border. Over the years, these yielded more than 130,000 diamonds mostly from bulk sample tests (including sizable diamonds weighing >28 carats). In addition, more than 600 high-quality crypto volcanic anomalies were found by the Professor that suggest Wyoming, Colorado and Montana are underlain by a diamond province of unparalleled size. Now here's where you come in. As a prospector and rock hound, start researching these and Walla - you may become the next DeBeers! 

Back to the Professor. While working for an international diamond company, he found another group of 50 depressions along Interstate 80, within sight of the state capitol. Are these diamond pipes? They sure look like they could be. But to this day, they still have not been drilled or sampled.

Before finding these depressions, the Professor was looking for diamonds in the Leucite Hills near Rock Springs but he found another gemstone everyone else missed. Peridot! He took 13,000 carats along with many angry ants from their anthills and from outcrop at Black Rock - this was the first time peridot had been described in Wyoming! And now, many rock hounds have taken advantage of his discovery and collected this beautiful gemstone.

In 1981, he predicted gold would be found near Casper - simply by studying the geology. This became one of the more impressive finds in the past century in Wyoming, and will end up in a major gold mine some day. Imagine you are a gold prospector. You find a gold deposit! How do you feel? Well the professor not only found a gold deposit, he found a whole new gold district that everyone else missed. Gold districts have many gold deposits with similar deposits in a small geographical area and the Professor predicted this one would also have a major gold deposit along with many other gold deposits. This became known as the Rattlesnake Hills gold district. Geologically, it is what geologists call a greenstone belt (also known as gold belts in Australia, Canada and Africa). Not only did the professor find the Rattlesnake Hills greenstone belt, he found gold at several other locations and then mapped the South Pass greenstone belt and Seminoe Mountains greenstone belt and not only found gold in these belts, but also in the Elmers Rock greenstone belt. We may never know how many gold deposits the Professor found, but it is clear he found dozens! And with the mapping of the greenstone belts, the GemHunter also provided a clear picture of Wyoming greenstone belts (or gold belts). Thus, Dr. Robert Houston, Dr. Paul Graff, Dr. Karl Karlstrom, Dr. George Snyder and the GemHunter (Professor Hausel) gave future generations a picture of Wyoming's Precambrian geology that simply did not exist before these pioneers.

Following the discovery of several significant gold anomalies at the Rattlesnake Hills greenstone belt, mining companies and consultants flocked to the area to explore and discovered other gold deposits. After more than 3 decades of drilling, a significant, large-tonnage, low-grade gold deposit was found at Sandy Mountain: right where the Professor told the University of Wyoming Research Institute it would be - but Wyoming refused to provide any increased funding for this kind of research. 

A large (34 ounce) gold nugget recovered from Rock Creek
in the South Pass greenstone belt of Wyoming.
The Professor predicted at least two generations of gold deposits would be found in this greenstone belt - gold associated with very old (Archean age) greenstone rocks and gold associated with replacement deposits, breccia pipes, and with younger volcanic rocks (Tertiary age). In other words, the Rattlesnake Hills has the best of both worlds. Greenstone belts are well-known for rich gold deposits, such as Yilgarn greenstone belt in Australia, which hosts 30% of the world's gold reserves and 20% of the world's nickel reserves. And the associated breccia pipes related to younger volcanic rocks are similar to gold deposits mined at Cripple Creek, where more than 23 million ounces of gold have been mined. Will the Rattlesnake Hills turn into another Kalgoorlie or Cripple Creek?

Following the GemHunter's discoveries, a few companies drilled. ACNC found more gold: Newmont Gold found a million ounces at Sandy Mountain, but walked away from a >$1 billion gold deposit. Another company recently began exploring Sandy Mountain and hit more gold! Lots of gold. It looks like they could have another Cripple Creek. The Professor felt he had found a giant breccia pipe between Sandy Mountain, Oshihan Hill and Goat Mountain - the mother lode but could not get funds from Wyoming to drill.

The Duncan gold mine at South Pass, Wyoming. 
The Professor wrote about many of his discoveries in more than 1000 books, papers, and abstracts and was in demand for talks and lectures and traveled all over North America to mining conferences and to visit various rock hound groups to tell the rest of the world about Wyoming. He became the spokesman for Wyoming's mineral resources and brought in dozens of mining companies, consultants and others who spent $millions in Wyoming in the search for the mother lode. It could easily be argued that no one in Wyoming had been more productive in the historic past when it came to increasing our understanding of Wyoming's mineral resources.

While mapping South Pass in the mid to late 1980s, the Professor made many more discoveries and wrote another book “Economic Geology of the South Pass Granite-Greenstone Belt, Wind River Mountains” (1991). Not only did we find quartz with visible gold using this book, we came across people who attended some of the Professor's field trips and had picked up specimens that should be in museums. The Professor gave his free time to teaching others about geology and prospecting in more than a hundred field trips and free seminars. Because of the Professor, Wyoming became Rock Hound heaven.

Mining gold from the dry placers at Dickie Springs. Prospectors follow up
on Dr. J.D. Love's research south of South Pass.
In South Pass, he predicted the Carissa mine would be a multi $billion gold deposit. It could be one of the largest gold deposits in the West. So what did the State of Wyoming do, they purchased it for an undisclosed amount with your taxes and made it into a picnic ground so no one could ever mine it again!

Now we see the footprints of Dr. J.D. Love. Dr. Love made many discoveries and is best known for his work on uranium as well as putting together a detailed geological map of Wyoming. In the South Pass area, he and two other members of the US Geological Survey researched the Oregon Buttes area to the south of South Pass and predicted (based on sampling and drilling) that this area has 28.5 million ounces of gold! It all remains mostly untouched. He also found a similar deposit with Jack Antweiler to the north at McGraw Flats!

Back to the Professor - The GemHunter rediscovered gold in the Seminoe Mountains in 1982. An honest to goodness rush followed as hundreds of geologists and prospectors flocked to the area. Then he found gold in the Sierra Madre, the Medicine Bow Mountains - more rushes.

A petrified Sequoia tree in the Wasatch Formation near Buffalo, WY (photo
by Wayne Sutherland, 1979).
Then he went to Alaska as a geological consultant in 1988 and 1989 for West Gold thanks to his friend Dr., Paul Graff. While searching for gold, one of the largest gold deposits in the history of North America was found. Seven geologists (three from Wyoming) found a gold deposit that now is reported to contain more than 41 million ounces of gold! The Donlin Creek deposit, when mined, will produce 1.5 million ounces a year and will be one of the largest gold mines in history. To give a proper perspective of how huge this gold deposit is, particularly those who are fans of the reality show GOLD RUSH, the Donlin Creek discovery is so enormous that it contains more than twice the amount of gold mined throughout the entire history of the Yukon! It also contains more than 120 times the amount of gold mined in Wyoming throughout its entire history! So, my advice to any prospector: follow the Professor around in the field – he will find something else.

Over the years, prospectors and treasure hunters found many gold nuggets in Wyoming. A 7.5-ounce nugget was found at South Pass by a rock hound. Another treasure hunter from Colorado found more than 100 nuggets in Wyoming, another from Arizona recovered 399 nuggets in the Sierra Madre, and then there was a 34 ounce nugget found in the 1930s and a boulder full of gold found before then. Yes, there is gold in the Windy state. But there is more. In 1995, the Professor found platinum, palladium, gold and nickel at Puzzler Hill near Saratoga. How did everyone else miss this and all of the other discoveries - such as the largest iolite deposits and samples found on earth?

GEMS HERE THERE & EVERYWHERE A few gems were found in Wyoming besides jade: agates, jasper, a beautiful 2-foot long aquamarine from Anderson Ridge found by the late Elmer Winters. But when the GemHunter focused on gems, he made history, and there is little doubt if he had remained in Wyoming, dozens of more gemstone and gold deposits would gave been found by now.

Extraordinary jade from Wyoming
Several diamond deposits, pyrope, chrome diopside, peridot, spessartine, kyanite, ruby, sapphire, apatite, helidor, aquamarine, giant jasper deposits, common opal, fire opal, amethyst, precious opal, iolite - gems that were not suppose to be in Wyoming were found by the GemHunter. The discovery of gold in the Rattlesnake Hills and in Alaska were quite impressive discoveries, but then there were the fabulous and world-class iolite gem deposits found in the central Laramie Range.

It is said, that it is extremely rare for a person to find one world-class deposit - after all, there have only been a few dozen found throughout history. Yet, the Professor was part of the discovery team that found a world-class gold deposit in Alaska, he found a major gold district in the Rattlesnake Hills and then he found two world-class iolite deposits. He also identified significant gem kyanite deposits, a significant fire opal deposit (even though common opal had been mentioned in passing in the area by geologists of the USGS in the 1930s) and mapped opal and agate in parts of 16-sections of land, and then he mapped the two largest diamond-bearing kimberlite districts in the US, discovered a formerly unknown kimberlite district (Sheep Rock district), mapped the largest lamproite field in North America, and mapped the 250-square mile South Pass greenstone belt, the Seminoe Mountains greenstone belt, the Rattlesnake Hills greenstone belt, the Cooper Hill district and parts of the Silver Crown gold-copper district. In total, he mapped more than 600 square miles of geology in Wyoming.

At the time of discovery, this iolite specimen was the largest, single iolite
gemstone in the world. The gem weighed 1,750 carats and found by
the GemHunter in 1995.
Iolite discoveries. Iolite looks like tanzanite - only better to some collectors. It is an extremely rare, sapphire to violet blue gem. In 1995, the Professor found this gem with ruby, sapphire and kyanite and at the time, recovered the largest iolite gemstone in the world, a fist-sized specimen of 1,750 carats. This large iolite gemstone was found at Palmer Canyon to the west of Wheatland by the GemHunter. In addition to this gem, he recovered several dozen iolite gemstones, with many weighing a few hundred carats each. Nearby, ruby, pink sapphire and sky blue kyanite gemstones were also recovered.

Some of the first iolite and ruby gems
faceted from Palmer Canyon rough.
Then in 2004, the GemHunter found an iolite gemstone that weighed 24,100 carats at Grizzly Creek a few miles south of Palmer Canyon. There were much larger gemstones but he couldn't figure out how to place a gemstone weighing more than a million carats in his back pack! That's right, gemstones so large that it will require serious mining to get them out. He had predicted this deposit would occur based on geology and even wrote about it in 2000.

Then he came across the Sherman-Raggedtop iolites. Based on geology, this one could potentially host more than 2 trillion carats of iolite! But the Professor moved on before much could be done on this deposit after he discovered it. But based on exploration prior to the second world war, the Wyoming Geological Survey had estimated that this deposit contained more than 500,000 tons of cordierite - it was all assumed to be industrial grade. So, the GemHunter went searching and found very high-quality gem iolite along the edge of the deposit - every specimen he collected was a gemstone. Thus, if only part of this deposit is gem-quality, we are talking about trillions of carats of gemstones! Almost enough to pay for part of the Obama National Debt. But this deposit remains mostly untouched. According to the GemHunter, there are likely several more gem iolite deposits in this part of the Laramie Mountains.

Some Sweetwater agates found in the opal fields of Wyoming.
Opal Discovery. Opals? The GemHunter mapped one of the largest opal deposits in North America south of Riverton. Opals everywhere – some are larger than 100,000 carats sitting right next to the state highway! While mapping, he found billions of carats of common opal, agate, Sweetwater agate, the first fire opals reported in Wyoming, and the first precious opal verified from Wyoming. So kick around a few rocks, and keep your eyes open, you are likely to find a new mineral deposit or occurrence, maybe even a whole new district. But the GemHunter didn't find this deposit. It had been mentioned in passing in a couple of early publications by the US Geological Survey that some rocks were opalized, but no other descriptions. While talking to a rock hound group in Riverton, a rock hound had mentioned he had picked up some opal in the area, so the GemHunter decided to go have a look and he found boulders of common opal sitting along the side of the roads, an entire hillside of fire opal, and a few traces of precious opal along with all kinds of agates and Sweetwater agates. It was just another example of no one every bothering to look. An recently, the GemHunter believes he may have identified another similar deposit near Douglas Wyoming that is described in his recent gemstone book. If he were still in Wyoming, no doubt another significant gem deposit would have been identified by now, but instead, the deposit sits near the Interstate gathering dust. Makes one wonder?

Specularite with malachite from the Hartville uplift, WY
HISTORY OF PROSPECTING The following is summarized from a free pamphlet on rock-hounding published by the Wyoming Geological Survey. Gold was found by Spaniards 200 years ago in Wyoming. However, recorded history indicates that gold was discovered in Wyoming in 1842. Fur trappers found gold in streams in the Wind River country, which at the time was part of the Northwest Territory. Several years later, in 1863, immigrants passing near Oregon Buttes along the Oregon Trail to the south reported finding gold along the trail. Four years later, after the region had been made part of the Dakota Territory, prospectors working further north discovered a rich lode along Willow Creek at the base of the Wind River Mountains. This led to the sinking of the Carissa shaft. South Pass City was organized within site of the gold mine.

Hundreds of prospectors rushed to South Pass. Reports vary, but 2,000 to 10,000 may have populated South Pass City at the peak of the rush. Gold was soon discovered at several nearby localities. Other towns rose from the dust. Hamilton City (Miners Delight) and Atlantic City reported populations of 1,500 and 500 people, respectively. Pacific City to the south claimed a population of 600. A few years later, after the region became part of the Wyoming Territory, gold discovered on Strawberry Creek led to the establishment of a town named Lewis Town (also known as Lewiston). Soon Wyoming recorded other gold discoveries in the Seminoe Mountains, the Medicine Bow Mountains, and the Sierra Madre and in the Black Hills. Gold has been found in every mountain range in the state and many streams draining these regions also have gold!

Copper-gold-silver ore from the Ferris-Haggarty mine,
Encampment district, Sierra Madre. This rich copper sample
is an example of mill rock that is found adjacent to volcano-
genie massive sulfide deposits.
Gold was King until near the end of the 19th Century. Then it found a Queen with rising copper prices and copper rose high enough it was considered a precious metal by prospectors. Rushes to the Absaroka Mountains, Sierra Madre, Medicine Bow Mountains, Owl Creek Mountains, and Laramie Range brought many prospectors to Wyoming. About the only major discovery was the Ferris-Haggarty in the Sierra Madre. To recover the rich ore, a 16-mile long aerial tramway was built to haul ore from over the continental divide from the mine on the west side of the range, to the Boston-Wyoming mill and smelter complex at the town of Riverside on the east side of the range. Copper was followed by platinum, palladium, asbestos, manganese, titanium, uranium, iron, coal, trona, bentonite, oil, gas and jade. Dr. David Love and Ray Harris made several uranium discoveries.

WHAT TO LOOK FOR Some general localities are described. A good addi­tion to the reading list would be a descriptive rock and mineral reference book to help you iden­tify some of the more difficult minerals.

Agates, Jasper, Petrified Wood Agate, jasper, and petrified wood are forms of chalcedony. Chalcedony is a compact or massive form of silica. Commonly, it forms by precipitation of silica-rich solutions as veins, as cavity linings, or by replacement in a wide variety of rock types.

Goniobasis agates from Delany Rim, Red Desert
By definition, agate imparts a dis­tinct color banding resulting from impurities trapped in the silica as it crystallizes, and petrified wood results when the original woody material is replaced by silica-rich solutions, usually during rapid burial by silica-rich vol­canic ash. Jasper is a brightly colored (red, brown, yellow) form of chalcedony.

Several distinctive varieties of chalcedony found in Wyoming are given descriptive or geo­graphical names by rock hunters. Some are so dis­tinctive that many rock hounds can give you the geographical location within in a few miles of where the sample was col­lected by merely looking at a hand-size sample.

Varieties of banded agate include Rainbow agate, which diffracts light into a rainbow spectrum of colors when thinly sliced. Rainbow agate is found in the Wiggins Forma­tion in the southern region of the Absaroka Moun­tains near Yellowstone, and in gravels along the Wind River north of Riverton. A red and white banded agate known as Dryhead agate is found along the Bighorn River northeast of Lovell and in sediments eroded from the Hartville uplift northeast of Gurnsey.

One of the more popular agates found in Wyoming is a very distinct and attractive agate, known as the Youngite. This is a very attractive, pink, silicified breccia cemented and coated with grey to blue-grey banded chalcedony. Youngite agates have only been found in eastern Wyoming in the Hartville uplift near Gurnsey.

Banded chalcedony from the Commonwealth mine, Arizona
Moss agates have a distinct dendritic pattern from iron oxide or manganese oxide in white to blue chalcedony. A distinct agate known as Sweetwater agate contains manganese oxide dendrites in dark blue to dark gray-blue chalcedony.

Sweetwater agates are found along the Sweetwater River and Sage Hen Creek west and northeast of Jeffrey City, respectively. For many years, no one could find the source terrain for the famous Sweetwater agate until it was discovered by professor Hausel when he was sampling and mapping the Cedar Ridge opal deposit south of Riverton.

The better places for petrified wood include the Absaroka Mountains, a place 35 miles north of Medicine Bow, along State Highway 130 between Saratoga and Walcott, and northeast of Farson. The most coveted samples are near Farson, known as the Blue Forest wood. These have cores of silicified wood enclosed by a light-blue to sapphire-blue chalcedony. In this same region, rock hunters used to find stumps of petrified trees standing more than 6 to 8 feet tall a century ago.

Goniobasis agate is a rock composed of dark-grey to black silici­fied fossil snails known as goniobasis gastropods. These rock agates are found in the Green River- Granger area north of Interstate 80 in Sweetwater County. Many other specimens have been found along Delany Rim near Tipton and Red Desert just south of Interstate 80. The better samples are dark brown to black in color, which in part is due to silicification.

Jasperoid breccia from the Granite Mountains
Jasper is reddish to tawny chalcedony, and is mineralogically and chemically identical to agate, with the exception of trace metals which impart the reddish to tawny color. Many jaspers have been found in the state, but some of the better known localities are in the Granite Mountains in central Wyoming. Two extraordinary localities occur in the Tin Cup and the Rattlesnake Hills districts. Professor Hausel identified an extraordinary jasper deposit in the Rattlesnake Hills which actually has some fossil leaves impressed in the jasper. The jasper mapped by him in the Tin Cup area is worth seeing. The jasper was exposed in an old mine and the mine and tailings are covered by some of the prettiest jasper and jasper breccia mankind has ever seen.

Deep green to blue stains on many rocks in mine districts usually are copper carbonates known as malachite and azurite. A bronze colored metal­lic mineral with a patina of purple and blue is known as chalcopyrite. When the copper weathers, they produce a copper-stained gossan that is a good place to look for visible gold. Some gossans cap copper-enriched zones at shallow depths where the water table is encountered. Gold, silver, lead, zinc and molybdenum may be found in association with copper.

Azurite (blue) with goethite and limonite (yellow and brown). Azurite is a
copper carbonate and will fizz just like a soda pop when dilute hydrochloric
acid is dropped on it. Another way to test for most copper minerals is to wet
the suspected minerals with dilute hydrochloric acid and then vigorously rub
a well-used (not new) rock hammer into the wetted copper mineral. If it is
copper, it will deposit a thin coating of native copper on your rock pick.
Sample collected from the Kirwin area, Absaroka Mountains, Wyoming.
About 30 million pounds of copper were mined in Wyoming’s past. Most was from the Encampment District, where several mines were developed to support the Boston-Wyoming smelter and mill complex at Riverside. One of the more famous was the Ferris-Haggarty. Ore from this mine was shipped from the mine site along Haggarty Creek in an aerial tramway. The tram ran from the mine, up the western slope and over the continental divide of the Sierra Madre, and down the eastern slope to a mill at Riverside. Some high-grade ore from the mine was incredibly rich containing 30 to 40% copper. For comparison, some of the major modern copper mines of today produce ore that has only 0.7% copper. In this same region, Professor Hausel found several massive sulfide copper deposits. Others were found by Conoco Minerals and a grad student from the University of Wyoming (Swift). So, the government decided to place many of these into roadless areas so they could no longer be explored.

Copper is also found in many other places in the state including the Absaroka Mountains in northwestern Wyoming. In the Absarokas, giant, copper deposits contain millions of tons of low-grade copper, with silver, gold, some zinc, lead, molybdenum and titanium that are worth more than $5 billion. And thanks to Uncle Sam, these now lie within wilderness, roadless and other areas that keep prospectors and rock hounds from prospecting.

Specularite (hematite) with bronze-chalcopyrite (copper-iron-sulfide) from
Puzzler Hill, Wyoming
Chalcopyrite (copper-iron-sulfide) is a brassy-orange, brittle, metallic mineral that weathers to limonite and a variety of copper minerals including malachite, black tenorite, and earthy red cuprite.

Malachite, a light- to dark-green copper carbonate, will react with dilute (10%), hydrochloric acid (Muriatic acid, a very weak form hydrochloric acid, will also work) by emitting bubbles of carbon dioxide, similar to the fizz in soda pop. If you place the same acid on tenorite or cuprite; you will find a thin plate of native copper will replace a well-used rock hammer after rubbing the hammer into the acid.

Diamonds, diamonds, diamonds! Diamonds are apparently recovered from streams as well as from a very rare rock known as kimberlite and sometimes from two of the rarest rocks on earth - lamproite and lamprophyre. Colorado, Montana and Wyoming have all three of these rocks and any prospectors should learn how to recognize them.

Raw diamonds from kimberlite - diamonds can be verified by using a simple
tool known as a Diamond Detective. Some diamonds are priceless, and others
have little value.
Some diamonds are the most valuable commodities on earth. Rare diamonds are valued at 200,000 times an equivalent weight in gold! Thus for their size, diamonds can be an extremely valuable commodity. Diamonds and other gems are mined from two rare rock types – kimberlite and lamproite, both of which are abundant in Wyoming. For instance, Wyoming has the two largest known fields of kimberlite in the US and the largest lamproite field in North America. Geological and mineralogical evidence supports that many more kimberlites and lamproites will be found in Wyoming. To date, most of the kimberlites that have been tested in Wyoming have either yielded diamonds, or favorable chemistry for diamonds.

Kimberlite sample

The first diamond pipe was found in Wyom­ing in 1960; but, the diamonds themselves were not discovered until 1975. Since then, more than 130,000 diamonds have been mined in a region south of Laramie extending from Tie Siding, Wyoming to Prairie Divide, Colorado. A large percentage of the diamonds that have been mined have been high-quality gemstones. A few diamonds larger than 28 carats have been recovered from the Kelsey Lake diamond mine along the Colorado-Wyoming border. The largest known diamond found in Wyoming weighed more than 6 carats.

Read about diamonds in a 1998 book “Diamonds & Mantle Source Rocks in the Wyoming Craton with Discussions of Other US Occurrences” and a 2002 book entitled “Diamond Deposits - Origin, Exploration and History of Discovery”.

Jade includes two mineral species: nephrite and jadeite. only nephrite jade is found in Wyoming. But it has been found in such abundance that it is considered synonymous with "Wyoming Jade", even though it is found elsewhere in the world.

Kimberlite with a large chrome diopside megacryst. Kimberlite is not
easy to identify, so you are going to need help with this rock.
It is a very rare rock that contains enough calcium carbonate
that it will react with dilute hydrochloric acid by fizzing.
Kimberlite volcanoes erupt giving off considerable amounts
of carbon-dioxide (that natural stuff that plants need to survive
and the EPA recently listed as a pollutant). Much of the carbon
dioxide is released into the atmosphere while a little precipitates
as calcium carbonate in the rock.
Many similar appearing rocks are mistaken for nephrite, such as rounded, stream-worn or wind-polished cobbles of dark gray to green amphibolite, metadiabase, epidotite, quartzite, serpentinite, and leucocratic (white) granite. These rocks can be distinguished from jade by any number of tests including some simple field observations. For example, amphibolite, metadiabase, and leucocratic granite typically have a granular texture that is lacking in jade; the freshly broken surface of quartzite tends to sparkle in sunlight due to the reflection of light off individual quartz grains; epidotite has a distinct pistachio green color and perfect cleavage; and serpentinite is relatively soft and often can be easily scratched with a pocket knife. In addition, serpentinite contains pockets of magnetite and is weak to moderately magnetic, unlike jade.

Nephrite jade is extremely tough and resistant to fracturing. As a result, rounded boulders of nephrite are nearly impossible to break with a hammer. Because of toughness and attractive appearance, nephrite, which has been termed the "axe stone", has been prized since prehistoric times.

Polished jade from Wyoming
Only carbonado, a black granular to compact industrial form of diamond is tougher than jade. However, gem-quality diamond lacks the toughness of jade and is easily smashed with a hammer. It is the toughness of jade, combined with its hardness that makes the gemstone carvable and durable.

Its hardness, ranges from 6 to 6.5 (or about the same hardness as a steel file). The green color in nephrite jade is the result of iron within the crystal lattice. When iron is absent, the mineral is practically colorless to cloudy white, resulting in a variety known as ‘muttonfat jade’. Other colors also depend on the abundance of iron in the crystal lattice, and these include translucent, emerald-green ‘imperial jade’; ‘apple-green’ jade, ‘olive-green’ jade, ‘leaf-green‘ jade, ‘black‘ jade, and ‘snowflake’ (mottled) jade. The greater commercial values are attached to the lighter green, translucent varieties.

Deposits of nephrite jade are accompanied by distinct alteration mineral assemblage that can be used to help locate hidden jade deposits. Where found, the jade is accompanied a distinct, mottled pink and white granite-gneiss with secondary green clinozoisite, pink zoisite, pistachio green epidote, green chlorite, as well as white plagioclase which is pervasively altered to white mica.

When found, jade may be covered with a cream to reddish-brown weathered rind. But when naturally polished with a high-gloss waxy surface, known as 'slicks', the jade is usually recognizable.

Sapphire and ruby are gem corundum. Corundum the second hardest known naturally occurring mineral, can be recognized because it will only be scratched by diamond, and is usually found as hexagonal prisms with distinct rhombohedral cleavage.

Rubies cut from red corundum from Palmer Canyon, WY
The deep red variety of corundum is termed ruby. All other colors of gem-quality corundum are known as sapphires – thus sapphire can be blue, green, pink, yellow and white. Some rare varieties of corundum may contain small mineral inclusions of rutile aligned in specific, crystallographic directions forming three lines oriented 120° to one an­other. These will produce a star effect when light if reflected from the mineral, and are known as star rubies, or star sapphires.

Gem quality sapphires and rubies are rare; however, a few crystals (including star rubies) have been reported from in the Granite Mountains north of Jeffrey City. Other rubies and sapphires have been found in the Palmer Canyon area of the Laramie Mountains west of Wheatland. Professor Hausel discovered that many of the Wyoming ruby and sapphire deposits occurred in a rock type known as vermiculite. Using this information, he found a half-dozen ruby deposits in vermiculites in Wyoming.

Gold is heavy, malleable and warm yellow metal. When scratched with a knife, the yellow flake or nugget will have a distinct gold­-colored indentation. Gold is also very heavy, and is 15 to 19 times heavier than water. For comparison, quartz is only about 2.8 to 2.9 times heavier than water.

In lodes, gold is often found with sulfide minerals. These may include pyrite (iron-sulfide), also known as fool's gold, arsenopyrite (iron-arsenic-sulfide), and chalcopyrite (copper-iron-sulfide). Pyrite can fool many people. It is often mistaken for gold; however, pyrite is much lighter and forms brass-colored, brittle crystals that often have cubic (6-sided) or pyritohedral (12-sided) habit. Unlike gold, pyrite is not malleable and can be easily crushed to a dark greenish-grey powder by striking the mineral with a rock hammer. Scratching a streak plate (a rough, white piece of tile) with pyrite will also leave a distinct black streak of powder on the tile. 

But pyrite sometimes contains hidden gold within its crystal structure - it can hide as much as 2,000 parts per million gold (this would be equivalent to a ton of pyrite containing about 60 ounces of gold). The gold in the pyrite would not be visible; unless some the mineral had oxidized and was replaced by limonite (a hydrated iron-oxide that is essentially rust) producing what is known as gossan, or boxworks.

Gold found in Douglas Creek, Wyoming
A gossan is essentially a reddish- to yellowish-brown, iron-rich mass found in some veins and faults. Gossans provide excellent places to search for gold, since limonite produced by the oxidation of gold-bearing pyrite, may contain specs, rods, or masses of visible gold. The better places to look for visible gold in gossans are in web-like, honeycomb, vuggy zones known as boxworks. Boxworks result from oxidation and removal of the pyrite, leaving behind silicified ridges, or outlines of the former crystals. Gold, however, being relatively inert, will remain in place, and can sometimes be found on the boxwork ridges.

Other sulfides found with gold include arsenopyrite and chalcopyrite. Arsenopyrite, a brittle, silver-metallic, mineral, will oxidize to a greenish-yellow limonite known as scorodite. When arsenopyrite is struck with a rock hammer, a garlic odor will be detected. This is due to arsenic in the sulfide. Some arsenopyrite can potentially hide as much as 1,000 ppm gold in its crystal lattice.

One mineral that is more often mistaken for gold than pyrite, is mica. Mica is often found in both lodes and placers. Each year dozens of people bring samples of mica to the WGS believing they have found the 'mother lode'.

Note the reddish brown rock in the back ground of this photo taken in the
San Juan Mountains of Colorado - this is an excellent gossan
In general, gold is found in lodes and placers. The term 'lode' simply describes an in situ mineralized vein or fault as opposed to a placer, which consists of reworked, detrital, heavy minerals concentrated in active or inactive stream gravels. Veins generally form narrow sheets of quartz, whereas most faults consist of vertical to near vertical sheets of intensely deformed rock that often contain quartz veinlets and boudins (lenses). When mineralized, the gold values in lodes are typically erratic along much of the length of the structure and random sampling may yield only trace amounts of gold. However, periodic ore shoots (enriched zones) are sometimes encountered. Some of these pockets may average more than 1 ounce of gold per ton. At such high grades, the gold will often be visible to the naked eye and individual pieces of rock may produce specimen-grade samples, especially when ore grades run higher than 1 ounce per ton.

Gold has been found in all of Wyoming’s mountain ranges as lode and/or placer deposits. Some of the better places to search for gold include the Wind River, Seminoe Mountains, Medicine Bow Mountains, Mineral Hill, and Sierra Madre.

The best place to search for specimen grade gold samples in Wyoming is the South Pass district, along the southeastern margin of the Wind River Mountains. The district encloses several gold-bearing faults (shear zones) and some veins. Many of these are located on maps published by the Wyoming Geological Survey, and there thousands of feet of gold-bearing shears in this region that have never been seriously prospected!

This area is also a good place to search for specimen-grade samples. For example, some ore recovered from the Carissa mine in 1908, assayed as high as 260 ounces per ton gold. The Miners Delight mine at South Pass was also a fairly good source of gold. Downslope from the mine, historical reports indicate that water was pumped from the shaft and used to mine Spring Gulch. Several 1 and 2 ounce nuggets were found in the gravels including one 6 ounce nugget. One lump of specimen-grade quartz was found in 1873 that was as large as a water bucket. According to one witness, it looked as if it contained a pound of gold. In nearby Yankee Gulch, northeast of the Miners Delight mine, 8 to 15 ounces of gold were mined per day including one nugget that weighed nearly 5 ounces.

In the central part of the district, the Rock Creek placer produced one fist-size chunk of quartz filled with an estimated 24 ounces of gold. A boulder found nearby in 1905, contained an estimated 630 ounces of gold!

Within the South Pass region, is the Lewiston district, located east of the South Pass District. In the 1890s, a 500-foot strip of gravel was mined at Wilson Bar along the Sweetwater River within the district, and yielded 370 ounces of gold. The gold was traced upstream to a lode named the Burr. In 1893, a pocket of ore intersected at the Burr lode yielded 3,000 ounces of gold. Some samples from this pocket was claimed to have assayed as much as 1,690 ounces per ton of gold! To the northeast, another lode named the Hidden Hand produced an ore shoot that yielded several sacks of specimen-grade ore containing 75 to 3,100 ounces of gold per ton! In recent years, some samples collected to the northeast of the Hidden Hand at the Mint-Gold Leaf lode assayed 1.29 and 3.05 ounces of gold per ton.

West of the Mint-Gold Leaf lode is a short drainage known as Giblin Gulch. The gulch cuts across the western end of the Mint-Gold Leaf shear zone, and drains into Strawberry Creek. In 1932, several nuggets were found in the gulch including some that weighed 5.2 and 5.3 ounces. Other nuggets found in this area included two that weighed 3 and 4.5 ounces. These were found in Two Johns Gulch in 1905. Another report indicated that five 'good-size' nuggets were found in the Big Nugget placer in 1944. The locations of the Big Nugget and Two Johns gulches are unknown, but possibly these are the same as Giblin gulch.

Douglas Creek district. A popular place for placer mining is Douglas Creek in the Medicine Bow Mountains of southeastern Wyoming. Gold nuggets in the area are typically jagged, suggesting that they were derived from nearby lodes. Many nuggets found in the creek and its tributaries are typically coarse and jagged, suggesting they had been derived from nearby lodes (the largest reported nugget weighed 3.4 oz). In recent years, several nuggets (0.5 to 1 inch in length) were reported from nearby Bear Creek which drains into Douglas Creek. Along the eastern edge of the district, nearly 40% of the gold recovered in Spring Creek, was in the form of coarse nuggets (a 2.5 ounce nugget was found here in recent years). If you prospect in this district, you should also keep an eye out for diamonds and platinum nuggets. Both have been found in nearby streams.

Nugget from Douglas Creek
To the north of Douglas Creek, is the Gold Hill district. Some specimen-grade samples have also been reported in this district in the Medicine Bow Mountains. Samples collected from the Acme mine in the past reportedly assayed as high as 2,100 opt! Specimen-grade samples from the nearby Mohawk mine reportedly assayed as high as 1,450 opt!

Seminoe Mountains district. The Seminoe Mountains lie near the central part of the state northeast of the town of Rawlins and north of Sinclair. On Bradley Peak, at the western end of the range, a small group of mines were dug on narrow quartz veins. Several specimen-grade samples of gold-bearing quartz were found on the mine dumps by Professor Hausel in 1981 which lead to a gold rush. For several weeks, every motel room in Saratoga and Rawlins was occupied from geologist from around the world trying to get the first claims in this area. Deweese Creek, which drains the Penn mines, shows very little evidence of placer mining. But based on the number of samples found with visible gold on the mine dumps, this creek probably contains some gold.

Platinum-group metals are closely associated with ultramafic rocks with high magnesium content, particularly those that are enriched in olivine, such as peridotites. A peridotite is a dark-greenish rock composed almost entirely of olivine with lesser pyroxene. Peridotites alter to serpentine, thus when prospecting for platinum, the prospector should investigate rocks described as ultramafic, peridotite, or serpentinite.

Platinum and palladium may be found in nuggets, grains, and flakes, and in certain sulfide minerals such as sperrylite (palladium sulfide), or may occur as impurities in some copper-sulfide minerals such as covellite.

Platinum-group metals have been mined from peridotites, nickel-copper-deposits in alkaline igneous rocks and in thick gabbros. However, the major platinum-group metal deposits are found in layered, mafic complexes such as the Bushveld complex, South Africa, and the Stillwater complex, Montana.

Platinum-group metals have been found in both placers and lodes in Wyoming. Platinum found in the Douglas Creek district occurs as grains or flakes. Platinum in nature has a specific gravity in the range of 14 to 17. One common impurity is iron: when in sufficient amounts, it may cause the platinum to be weakly magnetic. Platinum is a malleable, tough, bluish-gray (steel-colored) metal. It has a very high melting point, and is not affected by an ordinary blowtorch. It has a hardness of 4 to 4.5, and produces a shining silver streak when scratched by a knife.

A 12-carat, nearly flawless pink sapphire from the Laramie Mountains, WY
Platinum and palladium may occur as impurities in gold, producing what is known as white gold. This has a similar appearance to amalgamated gold. But unlike most amalgamated gold, white gold will have a consistent color throughout the metal. Whereas amalgamated gold may only have a bright silver rind produced by mercury that is distinctly gold-colored on the interior of a nugget.

Lode deposits of platinum-group metals are often found in layered mafic complexes. Currently, several platinum, palladium, and nickel anomalies have been recognized in southeastern Wyoming, in an extensive region that covers three mountain ranges paralleling a major fault zone known as the Mullen Creek-Nash Fork shear zone (also known as the Cheyenne Belt).

Some of the better anomalies have been identified in the in the Medicine Bow Mountains in Lake Owen and Mullen Creek layered complexes, and the Centennial Ridge district, and in the Puzzler Hill area of the Sierra Madre to the west.

The New Rambler mine, located along the northeastern edge of the Mullen Creek complex, was one of the only known mines in North America that produced platinum and palladium during the early 1900s. A cupriferous gossan was discovered here near the turn of the 19th century. A shaft, known as the New Rambler shaft, was sunk on the gossan. Ore from the mine included many copper minerals including platinum-bearing covellite and chalcocite, with some veins containing a rare mineral known as sperrylite. Nearly all of the important work on the New Rambler mine was done by Dr. McCallum.

The professor noted that the diamond pipes in the State Line area as well as some newly discovered pipes at Cedar Mountain southwest of the Leucite Hills had other gemstones that everyone again ignored. Beautiful gem pyrope known as Cape Ruby in South Africa, spessartine garnet, and gem-quality chrome diopside (known as Cape Emerald) and chrome enstatite. These later two minerals are very difficult for a novice to tell from emerald after they have been faceted.

Thanks to the efforts of a few geologists, Gemstones and gold are now abundant in Wyoming. Prior to the work and efforts of Ray Harris, Dan Hausel, Mac McCallum and Dave Love, little was known about these commodities. In fact, the state was just plain boring for rock hounds. Now, the Cowgirl state has diamonds, diamonds and more diamonds; rubies, sapphires, chrome diopside, opal, agate, jasper, gold and more gold; silver, palladium, platinum, helidor, aquamarine, spessartine garnet, almandine garnet, Cape Ruby, pyrope garnet, peridot, iolite, kyanite, apatite, chrysocolla, specularite, varisite, minyulite, malachite, azurite, onyx, zoisite, clinozoisite and jasperoid - all of these in addition to jade, and nearly every one discovered after 1975!

What a boring state Wyoming would be without the contributions of these four. Take a good look at Wyoming. Gemstones and gold were found every year since about 1975. Since these extraordinary geologists, no new discoveries have been made since 2006.