Thursday, June 28, 2012

Gold Processing & Extraction While Bear Hunting


Visible gold in goethite and quartz,
Mary Ellen Mine. (Steve Gyorvary specimen).
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. Many gold prospecting clubs are associated with the Gold Prospectors Association of America: and there are independent groups such as the Wyoming Prospectors Association. 

GRIN AND BEAR IT! And don't forget to support the NRA, unless you are willing to prospect grizzly country without a gun. Just imagine, panning in Wyoming, Montana, Alaska or even Washington DC and you look up just in time to see a grizzly licking its chops while staring at you 50 feet away. Sure, you can use that brand of bear repellant spray your university professor recommended even though he/she/it has never seen a grizzly except on TV. 

In the woods, a bear can easily sneak up to you, particular when it sees you are listed in the specials on the menu. Remember, it can charge as fast as 35 mph! But, you have that handy, dandy spice, errr, repellant in your pocket or back pack. How fast can you get that vial out of your back pack? "Oh, there it ...." "CHOMP".  

If you are lucky, you may have a little more than a second to get that thing out of your pocket, get the cap off, point and squirt, but I'll bet you end up served on the dinner special. That 700 to 1,500 pound grizzly can cover a short 50-foot distance in .... can you believe 1 second! Don't believe me, you can do the math yourself. And if you are lucky enough to point and shoot your little spice vial. I imagine that  bear mass, with all of its kinetic energy, is not going to stop easily - "splat and chomp!" 

So, the next time your hike and bike Berkeley professor tells you to use repellent, remember he/she/it is thinking about human sacrifice to keep the bears well fed. But if you have a gun, particularly a very large gun (12 gauge), 44 or 45 cal., you may stand a chance. But, why not a 357 magnum? Well, because one of our geologists in Alaska shot a typical, everyday, meat-loving black bear in-between the eyes at point blank range as it was trying to eat another geologist. All it did was give the bear a nasty headache. It knocked the bear down, but then it got up, and ran off until the next day, when it decided to come back looking for another geology snack.

GOLD PANNING POLLUTION. When I was in Wyoming, there was a faculty member in the  Geology Department who thought gold panners were polluting Douglas Creek in the Medicine Bow Mountains. Obviously, she never tried to operate a gold pan herself, otherwise she would not have made such a ridiculous statement.  Gold panning is a real, serious, pain in the neck (as well as the back and especially, the lower back). 
Gold Panning in the Medicine Bow Mountains, Centennial
Ridge district.
No one found gold at what was known as the
Mother Lode, but some found nice specimens of pyrite
(fool's gold)
 and some found almandine and pyrope garnet!
Pyrope garnet is a tracer 
mineral for finding diamonds!
So, somewhere upstream
there is an eroding diamond pipe
leaking pyrope garnet (and maybe diamonds) into
 the creek.

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. At 1600/ounce, that's only about $32,000 per week. Not bad for two guys.

Often we get use 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.

Panning is an easy - 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 an 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 is known as black sand (mostly magnetite with a few minerals such as ilmenite, zircon, etc), with specific gravities around 4 to 5, you are doing good. But be assured, you probably did not wash out much gold as it is 3 to 4 times heavier by volume, 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 serpentinite in northern California (Hausel, 1996). In Wyoming, we panned many gem-quality garnets, some diamonds, and numerous sapphires and rubies and found dozens of localities where gold had not been reported before (including the Laramie City landfill!) (Hausel and others, 1994). In samples panned in the Laramie Mountains near Vedauwoo, we found fluorite (easy to recognize in black sands - it is purple in this area and crushes easily) and many samples with chromian diopside and pyrope garnet near Eagle Rock. This suggests there are undiscovered diamond pipes! 

While searching for evidence of diamond pipes, we found distinct, small, structurally-controlled vegetation anomalies including one at (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 diamond pipes.

Not too far from Eagle Rock, we identified other possible diamond pipes that remain a mystery. These included 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. 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) we identified 42 highly suspicious cryptovolcanic structure 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 found while panning include 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 gem-quality iolite) near the old strong mine along the 9th street road in the Laramie Mountains.

And what else did we find? At one location in extreme northwestern Colorado, 4 diamonds, 17 rubies and 24 pyrope garnets were panned. 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. This diamond scam was amazing as it was an outcrop that was salted in 1871 and 1872 and the crooks scammed 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.

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.






















Thursday, August 26, 2010

Preparation For Gold Prospecting Trips


Claim post on Federal Minerals. I get questions about claim
staking, but I'm as confused as you are. Please contact the
US Bureau of Land Management for information and hope they
provide you with the correct information - they often don't.
As a prospector, you need to learn about maps. Topographical maps provide information on geography and show locations of hills, valleys, mountains, roads, trails, creeks and towns. Geological maps show rock outcrops in relationship to the geography and likely will have locations of mines, prospect pits, trenches, tunnels, veins, faults, shear zones and folds. Geological maps also provide information on types of rocks. 

Know what areas are open to mining claims. Much Federal land is open to claiming, but some is closed to claims. To find out what is open, visit you local BLM (no, not those idiots, the other ones) office. State land cannot be claimed but often can be leased. Private land cannot be claimed unless it has Federal Minerals under the private surface. One problem with mining claims is that new claims are constantly filed, and at the end of the fiscal year, others are not renewed thus claim maps change. Unfortunately, the BLM apparently decided to eliminate claim information on their website.  

Gold nugget found in Rock Creek, South Pass.
The BLM attempts to keep information up to date on this site, but like anything the government does, it is not always correct. So use it as a general guide for mining claims and claim activity then you need to follow up with research in the county courthouse. When prospecting in the field, watch for claim posts as these provide information on claim locations, although just because there are claim posts in the field, this does not mean that the claim is active or even legal. 

Other sources that are excellent for prospecting include Google Earth. With the aerial photos and associated maps on these programs, relationships between geology, topography, mines, prospects, roads and drainages can be seen from the air prior to visiting a area of interest. 

LEWISTON GOLD DISTRICT. Schedule a trip to the Hidden Hand gold mine and vicinity in the Lewiston district of the South Pass greenstone belt in Wyoming. The legal description for the Hidden Hand mine is SE section 5, T28N, R98W and map coordinates are 42o25’30’N; 108o32’39”W. Thus, if you examine the Radium Springs quadrangle and find section 5 with the Hidden Hand mine labeled on the map, it is in the southeast quarter of that section. Or by using the map coordinates, you should be able to zero right in on the mine with Google Earth.

Inside the power house at the Vulture Gold Mine ghost town, Arizona.
Topographical maps cover the area include 2 degree sheets (scale 1:100,000) and 7.5 minute sheets. The 2 degree sheets are especially useful. These can be neatly folded and carried in a shirt pocket, glove compartment, or day pack. They represent general maps covering broad regions that are great for planning field excursions and contain information on roads and geography. For greater details, 7.5 minute quadrangles (scale 1:24,000) are invaluable. Topographical maps are available at some sporting goods stores, outfitter stores, the WGS, US Geological Survey (USGS), University of Wyoming Geology Library and local colleges and libraries. The WGS and USGS will also have geological reports and geological maps, many which can be ordered on-line or over the phone.

 The coordinates of the Hidden Hand mine places it within the Radium Springs quadrangle near the top of the map. The map to the north is the Atlantic City map which may also be useful. Geological maps provide important geological relationships associated with the mine, such as rock types, nearby structures such as faults, shear zones, folds. Find a copy of the geological map of the Radium Springs quadrangle (Hausel, 1988e). Other geological maps in this area that will be of use Atlantic City (Hausel, 1989), Miners Delight (Hausel, 1992e) and South Pass City (Hausel, 2007). Now find a copy of Report of Investigations 44 (Hausel, 1991a). This report will be useful as it is a detailed discussion of the geology and gold at South Pass. Another report that will be useful when learning geology and rock types of the area is Reprint 49 (Hausel and Love, 1992). This report was put together for the Wyoming Geological Association and describes important rock outcrops and will lead you on a personal field trip through South Pass. Now, see if you can find Wyoming Geological Survey Bulletins 68, 70, 71, and 72.

A 7.5 ounce nugget found in tributary of Rock Creek, WY
The Hidden Hand mine is located about 8 miles east, southeast of Atlantic City along the Lewiston road (also referred to as the Oregon trail road) south of both the Lewiston ghost town site and Strawberry Creek. The mine is on a patented claim. Patented claims are claims filed under the 1872 mining law that had enough value the government allowed the claimants to purchase the property at a fair market price. This was done in the 19th century to try to stimulate interest in mining and development of the West (something the government today no longer does - now they just discourage development and protect bugs, flowers and dirt). Today, it is impossible to patent claims. Although I never had access problems to this mine because it sits in the middle of BLM ground surrounded by vast, empty, wasteland, it could easily be blocked off. There is a very disturbing trend that non-mining people buy patented mining claims and then close it off because they feel they have something of value when they have little to nothing other than coyote pasture. This is what has happened to many of the diamond deposits in the State Line and Iron Mountain districts. If it isn't the democrats stealing our future, it's the government stealing our land. Have you seen what the legislature did to the Carissa mine? This once potentially productive gold mine (it likely has more than a million ounces of gold in the ground) is now Wyoming's version of Disneyland.

When this district was mapped (Hausel, 1986c) I stayed in a tent near Lewiston for much of one summer and did not see another person all summer. But that was 25 years ago. Maps that cover this area include the Radium Springs 7.5 minute (1:24,000 scale) topographic and geological maps. 

Now if you examine Google Earth, you should see distinct foliation (closely spaced lines) in the Miners Delight Formation metagreywacke that trend to the northeast. The rocks in this area are folded, faulted and turned on end. Also noticeable is the alignment of the Burr Mine with the Hidden Hand mine and this trend parallels regional foliation. A nearly east-west to northeasterly trending line of vegetation is visible southwest of the Hidden Hand that represents a cross-cutting shear zone that intersects the primary shear at the Hidden Hand. There are several prospect pits and a number of backhoe trench scars (some remain open, others are reclaimed) cut perpendicular to the primary shear zone.

A portion of the Radium Springs Geological Map near the Hidden Hand mine by the author showing shear zones and mines in this part of the South Pass greenstone belt. Greenstone belts are famous for gold in veins and shear zones.

A few things to note on the map: (1) the mine is located at the intersection of a group of shear zones (wiggly lines). At least 5 shear zones (faults) are apparent in the field and on aerial photos. Because of this, the mine shaft sits in highly brecciated and incompetent rock. (2) The mines (black and white squares) and prospect pits (x’s) line up on the map and on aerial photos as these essentially follow the shear structures that are buried under a few inches of dirt. (3) The Hidden Hand shear zones are offset along faults (dark, solid bold lines) to the south (where they appear to terminate) and to the north at Strawberry Creek. (4) A few hundred feet of the shear structures continue under much younger rock and dirt labeled as Tu along the bank of Strawberry Creek. Thus there is likely some gold sitting under Tu. (5) Strawberry Creek and Burr Gulch likely accepted much of the eroded gold eroded during the past, thus downstream from these shear zones (to the east) would be a very good place to prospect for placer gold.
 
The shaft was sunk on a 10- to 30-foot-wide, N40oE-trending, 62oNW-dipping shear in chloritized, hematitic metagreywacke (the normally black rocks actually have a slight reddish to greenish hue due to rock alteration) The shaft was 110-feet deep and the shear was explored by at least 640 feet of drifts prior to 1926. Ore from the 30-foot level was reported to run as high as 75 opt Au (ounces per ton in gold). In 1916, about 1000 tons of ore with an average grade of 4 opt Au were reportedly stockpiled. Some specimen-grade material assayed 3,100 opt Au (since there are only 32,000 ounces in a ton, this indicates that this specimen contained 9.6% gold). I must point out that such high assays must be questioned and are suspect.

Samples of altered metagreywacke that I collected from the dump contained only trace gold (Hausel, 1989). This discrepancy suggests one of a two possibilities: (1) the reported assays were exaggerated or (2) that the property developed a reputation for producing excellent gold specimens that the mine dump was thoroughly picked over by collectors over the years. Little information about this district and mine has been published and the mine workings are inaccessible, thus it is difficult to provide much in the way of conclusions. In addition, the explored structure at the Hidden Hand mine exhibits considerable brittle deformation – something that is more typical of Laramide faulting (post gold mineralization) in this region.

When looking at the Hidden Hand or other prospects, mines and districts, try to learn as much as possible. Soon you will become an expert prospector. If a prospect has a vein, try following the vein on the surface: look for minerals that are described in the area. Try to visualize the vein in three-dimensions. What does the vein look like at depth, how far does it go into the earth: five feet, 500 feet or 5,000 feet? Does it pinch and swell at depth? Does it pinch to 1 inch, is it faulted at depth, does it swell to a giant vein? Of course you can’t be certain, but sometimes there are things around you that give you clues as to what might happen at depth. One minable gold vein in Yellowknife, Canada that I looked at several years ago was only 1 foot wide on the surface, but at 100 feet deep, it is 8 feet wide and rich in gold! What angle does the vein project downward into the earth? 

Outcrop of the distinctly dipping Vulture vein.
Now it’s time to call on the wisdom of Albert Einstein because we need to take a trip back into geological time. If we could step into a time machine and go back about 50 million years, what would the vein and surrounding topography look like? How far in the air would the vein (and surrounding country rock) have projected before erosion leveled the terrain to its current level: 20 feet, 200 feet or 2000 feet? Where did all of the gold in the eroded quartz vein go? If the level of erosion was 2000 feet, there could be considerable gold in the nearby creeks, gulches and draws. Is the vein folded? Folds in quartz are often great places to look for gold enrichment known as ore shoots. 
Limonite-stained gossan found in glory hole near the Vulture vein 
in Arizona.
As an example, look some photos of the Vulture gold mine in Arizona. The vein provides an excellent example of a dipping vein. The photo was taken along its strike (or trend) such that from the point the picture was taken, the vein continues perpendicular to the surface of the photo. Off in the distance is a wooden structure which represents part of the old headframe where a decline shaft was sunk along the vein. The dip of the vein or angle that it projects from the surface into the ground follows the flat surface along the left edge of the vein: here it dips about 40 degrees. But not only is the vein of possible interest. When you walk around this mine area, several things of interest pop up. To the right of the photo is a glory hole of altered rock that is gossaniferous and stained by tawny yellow to brown limonite that likely has some gold. This sits below the quartz vein. Sitting adjacent to this pit and on top of the rock unit is some eluvial and alluvial material that past gold miners thought might be of interest as they dug an adit into the material. In Arizona, there are lots of eluvial gold deposits that eroded from adjacent gold deposits (many are hidden today).  Also, by walking around the area, other things of interest include rehealed breccias (the angular rock fragments have been cemented together with silica rich material). These probably contain gold and in some of the rich porphyry copper districts in Arizona, similar breccia pipes are good indicators of mineralization at depth. And the possibility of older rocks in the Vulture area containing structurally controlled gold may be worth checking because the old vulture mill sits on old, folded schist and gneiss.