Friday, January 2, 2015

A Carrot of Gold?

When some think of gold, the word karat may come to mind. Or is it carrot or maybe carat? So did I just pan a vegetable of the stream? 
Schematic cross section through an ideal kimberlite
pipe showing carrot-shaped diamond pipe. Generally,

the vertical column from the blow to the maar is
about 5,000 feet. The blow is the enlargement at the
base of the pipe, and the maar is the volcanic orifice.

If you are a rabbit, possibly you panned out a carrot - but then again, you wouldn't be reading this blog. Carrots are good sources for vitamin A and good for attracting rabbits. I tried my green thumb in Gilbert Arizona last summer and planted a carrots only to discover few edible things grow in the Phoenix valley in the summer (other than prickly pear cactus - and its questionable if many of us would try to peel the skin off the cactus just to eat the slimy plant). All of my carrots deep fried when temperatures soared into the triple digits for a month. 

Personally, I still have difficulty adapting to Arizona’s extremely hot weather after living in Wyoming for  a few decades. But someone told me the other day that Arizona is like Wyoming, just in reverse. People just don’t go outside when temperatures hit -50oF in Wyoming and they don’t go outside when temperatures rise above 110oF in Arizona. I never thought of it that way. At least in Wyoming my truck had a heater; in Arizona it doesn't have an air conditioner (didn't need AC in Wyoming).

The word carrot comes from the middle French carotte that refers to the favorite food of that old "wascal wabbit". It has nothing to do with the other two homonyms carat and karat; except that diamond exploration geologists like to use the shape of a carrot to describe what the cross-section of a diamond pipe (volcano) might look like, but this is as close to diamonds a carrot gets.

One of the more than 300 cryptovolcanic structures discovered in the Colorado-Montana-Wyoming kimberlite (diamond) province (Hausel, 2014). This depression is filled with water in the spring, but has an unexplained vegetation anomaly, enriched carbonate soils. The anomaly is circular and characteristic of many diamond pipes in the Colorado-Wyoming State Line region.


Diamond pipes are largely carrot-shaped because they erupt with large amounts of highly pressurized gas and shoot out of the earth's mantle like a shotgun blast producing a maar-like volcano. When the kimberlite magma breaches the earth’s surface, the eruption is explosive and magma is ejected with country rock boulders and highly pressurized gas (water vapor and carbon dioxide). Some researchers suggest gaseous emplacement velocities could have been as rapid as Mach 3. 


Distinct depression associated with a diamond pipe in Colorado.
The diamond pipe sits under an open, grass-covered park.
Many kimberlites lack tree growth and often give people an
impression of an impact crater. This cryptovolcanic structure
was trenched and diamonds along with kimberlite
were recovered at shallow depth. Also note the fault trace marked 

in red. As a prospector, you should always walk these traces out
as far as they go simply because more than one kimberlite often
erupted along the same fracture. This is how I discovered some 
kimberlites in this region that were missed by others.
So much carbon dioxide was present in these eruptions that the EPA would have issued a citation to Mother Nature for releasing these toxic(?) fumes. (In 2009, Obama’s EPA listed carbon dioxide as an air pollutant. Prior to 2009, carbon dioxide was just a simple gas or plant food used by all plants, algae and many forms of bacteria needed to produce organic compounds and release the oxygen we all breathe [you know its coming, Obama will likely tax us for using oxygen]. It's good our government is watching out for us, otherwise we would not have been aware that such an important gas required for life was a pollutant).

Kimberlite (diamond) pipes (unless deeply eroded) have circular expressions in plan. This expression often looks like an impact crater. To see some very impressive diamond pipes, I recommend searching the Internet for Ekati Airport, NWT to see Canada’s premier diamond mining operation. Now search for the Big Hole Kimberley, South Africa”. This is another diamond pipe that was operated years ago and looks like an impact crater. Search throughout the Kimberley city limits and you’ll find other diamond pipes. 

Now take a look at Russia. Search for “Mir Mine, Russia also known as Mirnyy Diamond Mine. This will take you to one of the more impressive circular pipes. While you are looking at these areas, remember kimberlites almost always occur in clusters and often line up on linear fractures. In these three areas, you may find other circular anomalies that have not been mined that are likely kimberlite pipes.

In addition to finding the circular to roughly circular depressions, one needs to look for other characteristics, such as a group of circular to elongated depressions lining up on some kind of lineament. For example, take a look at the Lost Lakes in the Red Feather Lakes region of northern Colorado. You will find a group of lakes and depressions that sit on a distinct linear fracture that trends about N30oE. And when you take a look at the lakes along the northeastern extent of this fracture - wow - the lake shores look like they are coated with salt or blue ground. Several years ago, I visited these anomalies, and the soils are very carbonate rich - if you drop some dilute HCl acid on the soil, it will fizz. The country rock in the region is mostly granites and amphibolites which do not have any known carbonate. Now these are excellent cryptovolcanic structures and possible kimberlites. 

Years ago, I also came across a cluster of depressions in the Indian Guide district of Albany County Wyoming. All of these are situated along N-S to northwesterly fractures immediately west of the Iron Mountain kimberlite district, where dozens of kimberlites (including a couple of diamonds) were found years ago (Hausel and others, 2003). I tried to get the State to provide me with a grant to drill these, but to no avail. The state was much more interested in providing another agency with money to see how high a rare and endangered jumping mouse could jump (it turns out this rare mouse was not so rare after all - just a normal field mouse that was startled). So these cryptovolcanic structures remain  unknown as to why they exist - but the fact they are sitting along the western trend of the Iron Mountain kimberlites strongly suggest Wyoming is losing its marbles, or should be say, carats.

Now take a look at the Twin Mountains Lakes area near Cheyenne. I identified more than 50 interesting structures (depressions and lakes) in this area that are situated in a distinct regional fold in the Proterozoic amphibolites that could be an extension of the State Line kimberlite district. Some appear to be very large - could these be kimberlites?  No one has ever drilled or sampled these and they look like good targets to me. 

Now take a look at the Kelsey Lake kimberlites in Colorado. These were mined for a short time and produced many high-quality gemstones including a 28.3-carat diamond along with a diamond fragment from a stone estimated to have been about 80 to 90 carats (Hausel, 1998, 2014). As you examine Kelsey Lake, keep in mind this was at one time a diamond mine (1996) and there are at least two reclaimed kimberlites and much of the diamond ore was never mined due to legal problems. Also note there is still fresh blue ground exposed in the reclaimed area. In this region, there are also several unmined kimberlites - I know, because I mapped them years ago. They are all located in my new book.

Now here is something you want to really think about! The Kelsey Lake kimberlites sit right on the edge of Fish Creek and a small tributary to the south of the pipes. These streams must be filled with diamonds! In southern Africa, it was noted diamonds from the Kimberley region were transported more than 600 miles in the Orange River to the coast of western Africa. Now imagine where could all of those diamonds that eroded from Kelsey Lake be. Personally, I would map out Fish Creek and follow it and associated drainages for at least a hundred or more miles down stream.
Gem-quality diamond indicator minerals from the Sloan kimberlites, Colorado
Diamond indicator minerals (chromian diopside to the left and pyrope garnet to the right) in Sloan kimberlite specimens.
When one diamond company was taking samples for kimberlite in this area, they recovered a group of diamonds including a 6.2 carat gemstone in Fish Creek near Kelsey Lake - and they were NOT even looking for placer diamonds. 

Recently, I was notified by a prospector who read my book on Finding Gemstones, that he panned out a cache of diamonds including one just under 5-carats in weight out of a stream I had identified that would be an important diamond placer. Remember, tiny diamonds are almost worthless (as the boys on Gold Rush discovered in South America). But large gemstone diamonds can be valuable. 

If you decide to search the area for diamonds, there is a lot of private property, but also remember a couple of other things: (1) Fish Creek is long, (2) gem-quality diamonds can survive stream transport of at least 600 miles, (3) kimberlites yield other gemstones known as diamond indicator minerals, and (4) the State Line kimberlites have been eroded off and on for the past 600 million years and the largest portion of the kimberlite pipes (the mouths) have been eroded and the diamonds carried downstream (see the schematic cross section through a kimberlite above). It has been estimated that 2000 to 3000 feet of vertical column of kimberlite pipe in this area has been eroded. So, what are you waiting for?


The Carat
The carat may not be enriched in vitamin A, but if large enough, some carats can by a lot of carrots and vitamin A. A carat is what is used to measure the weight of gemstones. One carat equals only 0.0066 troy ounces, or 0.2 grams (200 mg). If you have a troy ounce of gold, this is equal to 31.1 grams or 155 metric carats (152 troy carats). Periodically, jewelers speak in terms of points and there are 100 points in a carat and each point equals only 2 mg (milligrams).

A flawless, 1,720 carat iolite gemstone I found at
Palmer Canyon Wyoming with some sapphire, ruby, and kyanite
gemstones - now that's a lot of carats. 
Now, if you have one troy ounce of gold worth about $1800 and compare this to a rare, pink, Argyle pink diamond worth about $1,000,000 per carat (unfortunately, I don’t have any Argyle Pinks), you will get a good idea at the incredible value of some gemstones. A one-carat rare pink diamond could be worth about 150 times more than a equivalent weight in gold! Not bad for a little crystal.

So where do pink diamonds come from? The pink in diamonds is thought to be the result of shear stress on the diamond, and such gems are thought to form at depth in a subduction zone unlike other diamonds mined in most kimberlites. The great majority of pink diamonds have been mined along the northern coast of Australia at the Argyle mine. To see this mine on Google Earth, search for “Argyle Lake, Australia” and the mine is a short distance southwest of the lake. Very recently, the largest pink diamond ever found was recovered from the Argyle mine. Described by many news outlets as a giant diamond, this one is only 12.76 carats (probably around 12 to 14 millimeters across or a little more than a half inch). As a comparison, the largest diamond ever found was the Cullinun that weighed 3,106 carats). But because of its rarity and color, the Pink Jubilee diamond may sell for as much as $10 million. When cut and polished, it will of course be even smaller.
A group of very expensive Argyle fancy diamonds on display at the
Argyle mine in Australia. I asked, but they wouldn't let me have
any of these.

The Karat
Now let’s look at another word that sounds like the other two words - the karat. Karat also has little to do with rabbits and vitamin A unless you purchase a gold pendant in the shape of a rabbit. Karat refers to purity of precious metals in jewelry. 

When you recover gold in the nearby mountains, it could be nearly pure, yellow gold or could be not quite as pure brassy electrum. Natural electrum refers to a mixture of gold and silver (>20% silver) that is sometimes referred to as white gold.

Natural gold (or precious metals in general) is alloyed with other metals including silver, platinum, palladium, copper, nickel and other metals. It is seldom pure (99.9%) and must be purified to produce the golden metal with few alloys. The purer the gold, the more malleable, soft, heavy and noble (resistant to oxidation and corrosion) is the metal.

Gold from Rock Creek Wyoming mined a short distance downstream from several gold-bearing lodes. This gold is a little whiter (brassy) than gold from some other nearby localities and likely has some silver. Some gold in this area was tested and found to contain as much as 11% silver.

The Rock Creek placer mine was closed by a 1942 War Minerals Board order. This suggests that the World War II miners were recovering gold worth $34/ounce at a profit. Today, gold prices are 50 times higher. Thus this placer likely is still minable. To visit this placer on Google Earth, search for “Atlantic City, Wyoming”.  Atlantic City sits in the upper part of the Rock Creek placer and is the place I figured I would have retired and ending up working for the Prospecting and Mining Journal - but things didn't quite work out that way. Now instead of shoveling tons of snow, I'm basking in the sun.

There are many other placers in this region that contain minable gold. One may be Willow Creek that runs through South Pass City. Willow Creek has a relatively small volume of gravel, but its location (cutting across the Carissa lode, the principal gold-bearing lode in the district) guarantees it will have rich pay streaks. However, Willow Creek was closed to mining by the Wyoming Department of Environmental Quality due to the toxic levels of mercury (whether imagined or real). During my research of this region over a seven year period, I did not find any evidence of primary mercury in the district and the possibility of large quantities of mercury being dumped in the creek by 19th century miners is unrealistic. Mercury was a valuable commodity in the 19th century. If some mercury were actually lost in the creek in the 19th century, it would have been a very small, finite source and mining would only serve to clean the creek bed. 

Pure gold is designated as 24-karat by jewelers: 24-karat gold being the purest at 99.9% gold that is also referred to as 0.999 fine. Being essentially pure, 24-karat gold is soft and can be difficult to some jewelry applications where a wearer of the metal has an active life style. This is because the malleability of pure gold insures such jewelry will be easily scratched. Gold purity can be defined by the formula:

P(karat weight) = 24 x Mpg/Mt (mass of pure gold /total mass of the material).

It is defined that there are 24 units (24 karats). Thus if you could find jewelry of 1-karat purity, it’s would not be something to brag about. One-karat would mean such jewelry is made up of an alloy of 1 part gold and 23 parts alloy metal(s). The percentage of gold in 1-karat would be determined by dividing 1 by 24, which is equal to 0.0416666. Rounding off this number gives 0.042, which is the fineness. To get the percentage of gold in 1-karat simply multiply fineness by 100 to get 4.2% gold.

Yellow gold from Smith Gulch at South Pass, Wyoming.
Two prospectors recovered 20 ounces per week
while prospecting Smith Gulch in the 1980s using
a small backhoe and a trammel. And keep in mind, this was
a placer that supposedly had already been mined out. 
Some jewelry is listed as 18-karat gold (18/24=0.750 fine). This consists of 75% gold. Another common mixture is 14-karat gold (14/24=0.583 fine) (58.3% gold); and 12-karat gold (12/24=0.500 fine) (50% gold).

12 karat gold = 12/24 = 0.500 (fine)

0.500 x 100 = 50%

Metals often alloyed with gold include nickel, copper, palladium, manganese, silver, zinc, aluminum, iron, gallium, indium, ruthenium, platinum, palladium and rhodium. By using various alloys, gold can be hardened or it can change color.

Using nickel and silver will give gold a subtle white appearance to yield white gold. The nickel provides not only white color, but gives the noble metal strength. However, some people are allergic to nickel. In this case, palladium, platinum, or rhodium can be used to substitute for nickel in white gold. Platinum-group metals are inert just like gold and will not produce allergic reactions (but they cost a lot more than nickel).

Rose and pink gold is formed by using copper as an alloy. The more copper, the deeper the pink color. The use of copper was popular in Russia in the past and this became known as Russian gold, which is now archaic, but the term still persists in the literature. Rose gold is 18-karat gold with 25% copper. Red gold is 12-karat gold (50%) with about 50% copper.

By adding zinc, one can produce less malleable and harder gold. Cadmium can be used to produce green gold. Other varieties include black, purple or blue gold. Purple or amethyst gold is a mixture of gold and aluminum that is 18-karat and brittle. Blue gold is produced by adding indium or gallium to 12- or 14-karat gold. By adding certain metals to gold, the gold can become more and more brittle, more corrosive, and may even discolor in contact with skin.

So karat is not a vegetable, but instead a measure of purity. If we were to weigh gold, the precious metal is weighed in ounces or measured in grams. But, then there is an ounce, and there is an ounce.

When is an ounce an ounce?
Weighing precious metals has caused considerable confusion. This is because there are two different ounces and few people indicate which ounce they are dealing with and not everyone uses the proper ounce for weighing precious metals. Most have the impression there are 16 ounces in a pound. Well, this is true when you are weighing something besides precious metals. The avoirdupois ounce we see on our bathroom scales when we weigh ourselves in the morning is the unit used to weigh objects in most English speaking countries. It comes from the Old French aver de peis which is interpreted to mean weight of goods. So how much your goods weigh in the morning is a result of how much indulgence you had during the previous night.

A 24 ounce gold nugget (some say 34 ounce nugget) from Rock Creek
Wyoming. Yes, I would be more than happy to accept this stone and weigh
it for the museum. 
The weight of precious metals is reported in troy ounces. The troy ounce was part of the Roman monetary system and many assume it refers to the city of Troy of the ancient Roman Empire. But it is instead named after the city of Troyes, France. The troy ounce is different from the avoirdupois ounce and equal to 20 pennyweights (another weight measurement used by prospectors). There are only 12 troy ounces in a troy pound and it takes 1.09714 avoirdupois ounces to equal a troy ounce. A troy ounce also has 31.1 grams while the avoirdupois ounce has 28.35 grams. There is a great website that does all of these conversions for you: .

The fire assay furnace at the Vulture mine, Arizona. Yes the assay house needs a little cleaning.
Gold has been prized since earliest times. Intricately sculptured objects and jewelry have been found in tombs in Iraq and Egypt where Jason and the Argonauts searched for the Golden Fleece. In Biblical times, placer miners used sheep fleece to capture gold in primitive sluices; thus this was the prize sought by Biblical Jason. Gold’s rarity is one reason why the metal became a symbol of wealth and power. The rareness of gold is due to it being formed during supernovae explosions when enough energy and pressure are possible to fuse atoms together to form gold. Without exploring stars (and likely the big bang) we would be without gold.

References:
Boyle, R. W., 1987, Gold – History and Genesis of Deposits: Van Nostrand Reinhold Company, 676 p.
Erlich, E.I. and Hausel, W.D., 2002, DiamondDeposits – Origin, Exploration and History of Discovery: Society of SME, 374 p.
Hausel, W. D. and Hausel, E.J., 2011, Gold –Field Guide for Prospectors and Geologists (Wyoming and Adjacent Areas): CreateSpace, 365 p.
Hausel, W. D. and Sutherland, W.M., 2000, Gemstones and Other Unique Minerals and Rocks of Wyoming – A Field Guide forCollectors: Wyoming State Geological Survey Bulletin 71, 268 p.

Tuesday, November 18, 2014

How to Find Gold Deposits

Would it be nice to be able to find gold deposits.  How about diamonds, colored gemstones, base metals and more?  In my recent books, I tell prospectors how to find these with examples, clues and locations. My three latest books work hand in hand providing details on gold deposits, how to find gemstone and diamond deposits, and describing how to identify minerals and rocks. If you are a prospector and enjoy the search for treasure, I hope you will enjoy prospecting with these books available at Amazon.





Sunday, October 6, 2013

Professor Hausel's Guide to Gold

Be careful of legends - Not Me! The Superstition Mountains! Many gold
legends are nothing more than a legend. Wonder why no one ever found the
Lost Dutchman mine? Well, maybe there is a mine out there, but why bother
there are plenty of known gold mines and properties around the West.
You've probably heard it before. "Gold is where you find it". Not sure what wise guy came up with that saying - but its true even though it should be obvious. But the problem is finding the "where you find it".  As a geologist who found more than 40 million ounces and possibly as much as 50 million ounces of gold in the ground, I think I have a nose for finding gold deposits and its not as hard as some make it out to be. I was awarded the Thayer Lindsey Award with 6 other geologists for making one major discovery, and also presented the 2004 Distinguished Service Award for many other discoveries.

Here are some suggestions for finding gold:
(1) Use science. Sounds pretty straight forward, but it is amazing how many promoters and scam artists out there profess using unscientific methods such as dowsing, witching sticks, legends, wet dreams and feelings to find gold. None of which have worked as far as I'm aware.
The iron stained (gossan) at the Vulture gold mine, Arizona. Learn what
you can about veins and how to follow them if you want to find gold.
When I was at the Wyoming Geological Survey, I had one dowser who would read my ICMJ prospecting and mining journal articles and next he would dowse the paper and ink maps in the article, sketch over a couple of pencil lines and then send me back a copy of the article to tell me where the mother lode was on each paper map. This went on for a few years and I finally lost touch with this person, so he was either recaptured or promoted to the obama administration. Another dowser would often send me advertisements for his school of dowsing (all hand written) for a variety of courses - and I kid you not, all of his classes sounded like part of the Twilight Zone. One of the better ones was how to find lost dogs and other pets using a dosing rod while flying over the country in a 747. Now if you don't laugh, you better seek help.

Gold nuggets from Arizona
Then there was Barbara - a little old lady prospector from Atlantic City Wyoming who knew where the gold was. It was apparently in other people's wallets. Barbara was well known for scamming people. She was only about 97 pounds soaking wet, a chain smoker, heavy drinker, and actually entertaining. She once sold a guy a jar full of gold at a reduced price. He was excited to show everyone his jar of gold at Atlantic City until he discovered he had a $5000 jar full of mica.  A short time later, the Atlantic City volunteer fire department was called out to put out a fire in Barbara's Cadillac.

Visible gold in rhyolite from Arizona. When you see this much gold - you
struck it rich. A rule of thumb. If you see one tiny spec of visible gold on a
rock sample, it will assay close to 1 ounce per ton. A rock with this much gold
likely would assay 100 ounces per ton.
On another day, Barbara latched on to a well-dressed tourist from Missouri who stepped into the Atlantic City Mercantile to ask directions. Barbara sat down with the unsuspecting visitor and tried to sell him a gold mine until he told her that he and his son actually owned the Mary Ellen mine.
Then there was a University of Wyoming professor. The professor had written on UW letterhead that 297,000,000 ounces of gold reserves had been identified at Pine Mountain west of Casper and near the Rattlesnake Hills. The only problem, no gold had ever been identified at Pine Mountain even though it has been a popular site for mining scams similar to the South French Creek area in the Medicine Bow Mountains. After this professor and others were investigated by the secret service, no charges were files as no money had yet exchanged hands - so the university promoted the professor.

One way to learn about gold is to read some good gold prospecting books. Then find a gold district near your town you can visit (don't buy and jars of gold) and get out on some mine dumps and start examining the area around the old mines. Look for any lineaments such as narrow quartz veins running towards the old mine dump you are standing on and walk along this vein. If there area lots of prospects on the vein, this start looking at the vein and learn all you can. See if you can follow the vein for a few hundred feet, a few thousand feet.
You might also look for linear depressions. These could be related to faults or shear zones. See if there is much in the way of prospects on these depressions. If there are, it is likely an old mineralized shear zone.

(2) Learn what gold looks like. This is important. Visit museums, look at photographs in books and on the Internet. Usually, the only thing that can be mistaken for gold is pyrite and mica and most mistaken mica for gold - like Barbara's friend at the Atlantic City mercantile. Years ago, I wrote an article for the ICMJ about some prospector living in Centennial Wyoming who had been jumping someone else's mining claim on the Middle Fork of the Little Laramie River all winter long. His name may have been 'John', but he used three different aliases when talking to me. Anyway, he mined all winter long using snow shoes to get to the claim and recover all of the gold he could, without being discovered. He told me he had a few barrels filled with the gold in his single wide trailer at Centennial, and finally brought in a couple of Ball jars filled with the material to verify his riches. You could see the disappointment when I told him he had some high-quality plant soil, but no gold.

Gold and silver-bearing vein north of Oatman, Arizona. The Gold Road vein is seen as the white quartz-calcite-adularia vein in the Oatman andesite. But also note all of the material to the left of the vein - this is a fault zone with quartz stringers and it likely contains low grade gold values.

Visible gold in quartz and hematite, Carissa Mine, South Pass
Wyoming
(3) Visit old mining districts. Read about the old mining districts you visit and keep in mind a couple of things - legends are just that - they are legends often concocted by an old prospector in a bar in the past after having one too many drinks. So why waste your time on some one's past drunk when there are still plenty of gold deposits to be found. It is extremely rare (actually rarer than getting the truth from a politician) for any gold mine to be mined out. Gold miners always leave a lot of gold in the mines and in the veins that they mined along. At one time not so long ago, gold prices were only about $18/ounce, then about $20/ounce and then $35/ounce. The other day, they were about $1,300/ounce. When gold prices were low, miners mined only the high grade material, typically material that assayed better than 0.2 opt Au. Today, some companies mine gold ore than averages only about 0.01 to 0.02 opt (ounces per ton) and better. So, in many old gold mines, the miners left all of the low-grade gold ore and sometimes missed a lot of high-grade gold ore. Think about it, how many times have companies gone back into old mines or old mine districts and began mining in an old mine. New mining districts are rarely found, so stick to the mining districts unless you have a lot of geological experience.

Gossan stained fault (shear zone) cut by the Giant King gold
mine in California. Gossans and faults like these should be
assayed
It is also worthwhile to visit old mines that were making good money prior to the War Minerals Board closing all gold mines in the US in 1942.  Some of these mines never reopened after the second world war for many reasons.



Giant King gold mine, CA. Note the iron stained (gossan) in the blue serpentinite. Some serpentinites have gold, some platinum and palladium, some will have nickel, and in California, some may have gemstones of benitoite or sapphire.
The Superstition Mountains - home to the 'lost. Dutchman gold mine.


Tuesday, November 20, 2012

GOLD, GOLD, GOLD!

GOLD, GOLD, GOLD!!!
A blog about prospecting for gold
Gold-lode quartz vein at the Vulture mine, Arizona
A gold mine at the end of the Rainbow - Duncan
gold mine, South Pass, Wyoming
At one time, justice was swift and thieves did not have to wait around on death roll for 20 years. People were a little more honest in those days because thieves were quickly thinned out of the population.
A 7.5 ounce nugget recovered from dredge tailings in Wyoming.



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Thursday, June 28, 2012

Gold Processing and Extraction


Visible gold in goethite and quartz, Mary Ellen Mine
If you decide to mine lode gold, you can keep it simple and dig for specimen-grade gold samples from veins and breccias. Although such samples with visible gold are rare and more valuable than the price of gold, if you have the right vein or ore shoot, they are worth pursuing. When ever you see gossans or tawny to brown limonite and goethite in quartz - look for visible gold! Gossans are something prospectors need to learn to recognize.

If you decide to mine your lode using open pit or underground methods - you will need deep pockets to pay for mining as well as permitting. In this case, it may be easier to start looking for a company that has the expertise and deep pockets.

Detrital gold is by for the best type of gold to search for as a prospector as it has already been mined by Mother Nature, and now it is up to you to figure out how to concentrate it. To extract placer (detrital) gold from a creek using a gold pan (not recommended as it will wear out your back), sluice, trommel, dredge or some other concentrating equipment, you will likely need permits from the State or Feds. The government is totally out of touch when it comes to permitting, as in most cases they will try to permit you to death. Some states may even require a permit to operate a gold pan on public property even though this would be as absurd as requiring a permit to operate a fork in a restaurant; however, Democrats were actually talking about this when I left Wyoming. One of the easiest ways to find out rules and regulations for prospecting in your state is to join a local prospecting club. The ICMJ Prospecting and Mining Journal has a number of useful resources you may want to check on.  Many gold prospecting clubs are associated with the Gold Prospectors Association of America: and there are independent groups such as the Wyoming Prospectors Association. When I was in Wyoming, there was a faculty member in the University of Wyoming Geology Department who thought gold panners were polluting Douglas Creek. Obviously, she never tried to operate a gold pan herself, otherwise she would not have made such ridiculous statements.  If you find the right creek, and have a backhoe and trommel, some people can make a nice living.
Gold Panning in the Medicine Bow Mountains. This lady was one of
several who attended one of my field trips to the Medicine Bow Mountains
in the historical Centennial Ridge district. I showed the attendees how to
pan for gold and then let them try their luck in the Middle Fork of the
Little Laramie River. No one found gold at what was known as the
Mother Lode prospect, but some found nice specimens of pyrite (fool's gold)
and several found almandine and pyrope garnet! Pyrope garnet is a
tracer mineral used to find diamond deposits! So, somewhere upstream
(or up-slope) there is an eroding diamond pipe leaking pyrope garnets into
the creek. In addition, many people discovered why it takes a strong back
to pan for gold.
Years ago, I met two prospectors from Lander Wyoming who were working Smith Gulch at South Pass while I was mapping the greenstone belt and old mining districts, and they were recovering about 20 ounces of gold per week (Hausel, 1991). At 1600/ounce, that's only about 32,000 per week. Not bad for two guys.

Often we get used to seeing gold pans filled with gold - this does not really happen in real life; so when we see gold filled pans, remember, the gold was found with some other equipment and placed in the pan for a photo opt.

To assist you in your prospecting, I have several publications that are available for free download on my website.

Panning is an easy process - it just takes a little confidence and a couple of pans full of sand and mud, and soon you will be an expert. Gold has a very high specific gravity (15 to 19.3) which means you are going to have to make a serious effort to wash gold out of your pan. So put a little effort into your panning. If you are ending up with a tablespoon or two of what are known as black sands (mostly magnetite with a few other minerals such as ilmenite, zircon, etc), those have specific gravities of around 4 to 5. Thus gold is going to be 3 to 4 times heavier than those black sands.

Stamp mill at Goldfields, Arizona
While panning for diamonds in California, we recovered a gemstone known as benitoite near Poker Flat and chromian diopside from serpentinites in northern California (Hausel, 1996). In Wyoming, we recovered many gem-quality garnets, some diamonds, and numerous sapphires and rubies from our pan concentrates and found dozens of localities where gold had not been reported before (one was the Laramie City landfill!) (Hausel and others, 1994). In several samples collected in the Laramie Mountains near Vedauwoo, we recovered fluorite (easy to recognize in black sands as it is purple in this area and crushes easily) and many samples with chromian diopside and pyrope garnet in the vicinity of Eagle Rock. This suggests there are undiscovered diamond pipes! While searching for evidence of diamond pipes, we found a distinct, but very small, structurally-controlled vegetation anomaly (41o17'39.96"N; 105o22'46.95"W) along the edge of Eagle Rock. This same area has several beaver ponds to the northwest, any of which could be hiding a diamond pipe.

Not too far from Eagle Rock, we identified other possible diamond pipes that remain a mystery. These included what I originally called the Bowling Pin Anomaly (41o11'15.39"N; 105o19'34.67"W), a circular depression with carbonate in soils that had a couple of bowling pins in the depression when I first visited it several years ago. The entire area has many such anomalies including the HJ17 depression (41o12'01.92"N; 105o19'10.46"W).  Further south (actually just south of the interstate) I also identified 42 highly suspicious cryptovolcanic structures of which anyone of them could be a kimberlite (diamond) pipe. All of these anomalies remain untested due to various access problems.

Arrastra gold concentrator. This was a very primitive grinder with large rocks
attached to a pivot at the center. A mule would walk around in circles pulling
a lever that would continue to drag the boulders over a trough where gold-
bearing quartz would be placed to be crushed.
Other minerals of interest that I found while panning included a lot of white material that was impossible to pan out. It was too heavy! So I stuck it under a black light and with short wave ultraviolet light, it exhibited strong blue fluorescence - it was scheelite (a tungsten ore)! This was recovered from samples (along with some gem-quality iolite) near the old strong mine along the 9th street road in the Laramie Mountains.

And what else did I find in my panned samples - at one location in extreme northwestern Colorado, I recovered 4 diamonds, 17 rubies and 24 pyrope garnets while dry panning. Wow, what a find!  Actually, this was the site of the historical 1872 diamond hoax fraud which occurred near what is now called Diamond Peak (Hausel and Stahl, 1995). This great diamond hoax was amazing as it was an outcrop that was salted in 1871 and 1872 and the prospectors scammed some US Senators (first time in history that scam artists scammed scam artists).

A primitive roller mill displayed at the Douglas Museum, Jerome, Arizona.
Eric Hausel stands adjacent to the mill.
Well, got to go, I hear my wife yelling at me. Until next time, happy prospecting from the GemHunter. You can also follow some of my thoughts on Facebook. And if you are interested in breaking rocks - and what rock hound isn't - you can follow me on my other Facebook pages at Arizona and International.

References Cited

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., 1996, Pacific Coast diamonds-an unconventional source terrane in Coyner, A.R., and Fahey, P.L., eds., Geology and ore deposits of the American Cordillera, Geological Society of Nevada Symposium Proceedings, Reno/Sparks, Nevada, p. 925-934.
Hausel, W.D., and Stahl, S., 1995, The great diamond hoax of 1872: Wyoming Geological Association Resources of Southwestern Wyoming Guidebook, p. 13-27.
Hausel, W.D., Marlatt, G.G., Nielsen, E.L., and Gregory, R.W., 1994, Study of metals and precious stones in southern Wyoming: Geological Survey of Wyoming Open File Report 94-2, 61 p.

Gold from Douglas Creek Wyoming. Photo shows gold recovered with the black sands removed (the penny is just used for scale). To remove black sands, simply wait until your panned concentrates are dry. Get a large and strong magnet, cover it with a paper towel and slowly sweep over the concentrates - whamo - nearly all of the black sands will be removed. What you have left is a little gold, garnets, mica and if you look close, you may even find diamond indicator minerals such as pyrope garnet, chromian diopside, picroilmenite, chromite and/or diamond. Diamond has a specific gravity of 3.5 and will often end up in the black sand concentrates. Much of the lighter colored material will be removed during panning: most of which will be quartz with a little feldspar. Quartz has a specific gravity of only 2.7.

Mining on Douglas Creek using a long tom and a
dredge on a rotating platform with shovel.







Gold nuggets in gold pan. The nuggets from Julian
Creek were recovered using a sluice and long tom
and not recovered in the pan.












Gold mined from Smith Gulch at South Pass using a backhoe and trommel.



Friday, February 10, 2012

Some of my Favorite Gold and Base Metal Prospects

Miners Delight mine, South Pass, Wyoming
Underground in the Carissa mine, South Pass, WY
Last night I was thinking about all of the gold, platinum-group metal, base and precious stone deposits I've looked at or studied. If one were rich and could get some senators in their pocket, they might be able to make a few mines. Anyway, these are my choices for some good properties.

1. Donlin Creek, AK
2. Rattlesnake Hills (Sandy Mountain), WY
3. Carissa, WY
4. Mexican Hat, AZ
5. Gold Coin, AZ
6. Lost Basin, AZ
7. Vulture Mine, AZ
8. Kurtz-Chatterton, WY
9. Bear Lodge, WY
10. Julian Creek, AK
11. Wolf, WY
12. Drum Mountains, UT
Goldfields, Arizona
13. Miners Delight, WY
14. Mineral Hill, WY
15. South Pass City-Atlantic City-Miners Delight shear complex, WY
16. Penn Mine Complex and altered zone, Seminoe Mountains, WY
17. Copper King, WY
18. Ferris-Haggarty, WY
19. Bannack, MT (and dozens of other gold properties in Montana)
20. Alder Gulch, MT
21. Confederate Gulch, MT
22. Whitehall, MT
23. Zortman, MT
24. Kendall, MT
25. Bear Lodge, WY (Au, REE, Th)
26. Puzzler Hill, WY (Au, Cu, Pt, Pd, Ag)
27. Bald Mountain Porphyry, Kirwin WY (Cu, Ag, Au, Pb, Zn)
28. The entire withdrawn Absaroka Volcanic Range, WY, MT (Au, Ag, Cu, Zn, Pb, W, Ti) (this range has $hundreds of billions in resources, reserves and deposits waiting to be found. But the USFS piecemeal withdrew the entire mountain range over the years).
29. Grizzly Creek colored gemstone deposit, WY (iolite, kyanite, ruby, sapphire).
30. Sherman Mountain colored gemstone deposit, WY (iolite, labradorite)
31. Colorado-Montana-Wyoming diamond province (diamond and other gems).
32. Tabor Grand Mine, WY
33. Duncan Mine, WY
34. Stockwork complex south of Sandy Mountain, Rattlesnake Hills, WY
35. Alkalic intrusive stocks in the Rattlesnake Hills, WY
36. Leucite Hills, WY (diamonds)
37. Copper Creek district, AZ (this district appears to have very high potential, but the US Government allows illegals to run freely through nearby federal parks closed to US citizens, makes it very difficult and dangerous to prospect.

Underground at the Mary Ellen mine, South Pass, Wyoming. Note the faulted
gold-bearing quartz vein in metatonalite.

Underground at Superior Arizona