|Twin Mountains crypto-volcanic structures south of I-80 between|
Laramie and Cheyenne. A few of the many 'kimberlitic' indicator mineral
anomalies discovered by the GemHunter that still remain
unexplored. This aerial photo shows a group of circular to elongated ponds
surrounded by considerable carbonate (white material) that are all
structurally-controlled by faults and sit within a distinct fold in Precambrian
gniess and schist in Wyoming.
Nearby, a group of chromian-diopside and pyrope garnet-rich lamprophyre breccias with many fragments of eclogite were initially discovered by a South African diamond mining company years ago, which was followed up by others including Dr. Richard Kuchera an more recently by UP Resources. Everyone who tested these lamprophyre breccia pipes found small micro-diamonds along the southern flank of Cedar Mountain in southwestern Wyoming.
|Large group of circular depressions (some filled with water) west of the Iron Mountain kimberlite district in the|
Laramie Mountains. These are all structurally controlled and also show evidence of caliche (calcium carbonate) and
lie within the Proterozoic age Laramie Anorthosite Batholith. These still remain unexplored for diamonds! Nearby,
the GemHunter also found evidence to two of the largest colored gemstone deposits in the world (still
unexplored!). False color infrared aerial photo over the
Indian Guide crypto-volcanic district. Note the dirt roads for scale.
|Sheared Sherman Granite (1.4 Ga) and weathered blue-ground (diamondiferous |
kimberlite) (Silurian-Devonian age) exposed in Dozer cut in the Colorado-
Wyoming State Line district (photo by the GemHunter).
Photos are not a good way to identify a mineral or rock as there are no physical properties one can use. Think about that for a minute - you are sending an image made of pixels - not rock. And nearly every prospector could use a course in photography as 90% of the photos I received in the past, are so poor quality, I'm not even sure if I'm looking at a rock, mineral or the family pet.
Photos are two dimensional representations of a 3 dimensional object and retain no physical properties of the specimen - one cannot conduct scratch tests or view inside the minerals to search for mineral inclusions. So it is best prospectors learn to identify diamonds themselves - or visit your state's geological survey - many have a staff member who identifies minerals and rocks for the public. I use to identify hundreds of rocks and minerals for mining companies and prospectors when I was at the Wyoming Geological Survey at the University of Wyoming - back in the old days when the Survey was a functional geological agency and was there to assist companies and the public!
|Giant, 620-carat diamond photographed at |
Wiseman’s Jewelry in Laramie (photo by the GemHunter)
I couldn't believe it! I took a couple of photos of this giant diamond - and it is interesting to note that most large diamonds have irregular shapes as seen in the photo to the left.
|Sketch of Santa’s Workshop in Canada, where |
many diamonds will be coming from this
Christmas (original pencil sketch by
|Former industrial brown diamonds are now worth considerable money. Brown diamonds include Cognac,|
Chocolate and other varieties that are now marketed as gemstones (photo by GemHunter).
Another interesting fact: of the diamonds recovered from the Wyoming pipes, at least 50% were gem quality. Just south of Laramie, more than 130,000 diamonds were recovered during exploration, and one commercial mine operated for a short time but closed due to legal problems rather than a lack of diamonds. The mine, Kelsey Lake, can be found on Google Earth along the Colorado-Wyoming border near Highway 287 (40o59’38.55”N;105o30’14.52”W). Then, there are more than 300 crypto-volcanic structures that I identified over the years as well as hundreds of diamond anomalies in Colorado and Wyoming! And this is only the obvious occurrences - most diamond pipes hide along structures and have to be found using airborne magnetic and conductivity (INPUT) surveys.
|The Kelsey Lake diamond mine, Colorado, extended north to the Wyoming|
border and produced many excellent gem-quality diamonds! (photo by the
The reason why diamonds were discovered in Colorado and Wyoming was due to accidents (McCallum and Mabarak, 1976). Diamonds are likely found by a prospector named Frank Yaussi from Fort Collins who operated a gold sluice along Rabbit Creek in Colorado at the location of the Sloan 1 and 2 kimberlite pipes. Frank had no idea that these were diamond pipes at the time, but he recognized diamonds in his placer concentrates - but no one paid attention to an old prospector (Frank Yaussi, personal communication). Anyway, Yaussi recovered some placer diamonds with gold. Later, he started selling some attractive, green, serpentine breccia for terrazzo that was mined on the hillside along Rabbit Creek sometime in the late 1960s or early 1970s. The terrazzo was cut and polished at a plant in Cheyenne Wyoming until the company went out of business after its polishing wheels were scratched beyond repair by the diamonds in the kimberlite! This was an actual outcrop of kimberlite (Sloan 1). It wasn't until 1975, a sample of peridotite recovered from a Wyoming kimberlite was collected by McCallum and Mabarak and sent to the US Geological Survey lab in Denver that diamonds were positively identified. While being prepared for research, the rock was cut and polished and carved several deep scratches in the carborundum polishing wheel. At that point, the rock as dissolved in hydrofluoric acid and several micro diamonds were extracted.
|Geological map of the Iron Mountain kimberlite district by W. Dan|
|Frosted cubic raw diamond. Note how greasy this |
diamond looks (fact #1)– something that is characteristic of
raw diamond (photo by the GemHunter).
|Raw diamonds with modified Octahedral crystal habits (photo by the|
|An extraordinary 14.2 carat octahedral diamond |
from the Kelsey Lake mine in Colorado
(photo by Howard Coopersmith).
Many diamonds from Argyle, Australia, Murfreesboro, Arkansas, and the Colorado-Wyoming State Line district exhibit resorbed crystal habits. And 4-sided tetrahedral diamonds are sometimes encountered that are distorted
|Note the surface of this slightly yellow diamond. It has several |
trigons on the surface (triangular depressions and plateaus)
seen on most natural diamonds. As a diamond prospector, you
need to become familiar with these and look for them
as well as look at the crystal’s luster – it should look greasy.
Sometimes trigons are in the shape of hexons (6-sided
depressions and sometimes as four-sided depressions,
but trigons are more common) (photo by the GemHunter)
|Parcel of fancy color diamonds from Australia (photo by the GemHunter).|
Corundum (ruby, sapphire), the next hardest naturally occurring mineral has a Moh’s hardness of 9. Thus, diamond will scratch corundum (fact #5). Corundum does not even compare to diamond’s hardness. The Moh’s hardness scale is a little misleading, as it is a 'relative' hardness scale and the difference in hardness between diamond (H=10) and corundum is much larger than that between corundum (H=9) and talc (H=1). A more exact scale is the Knoop scale, which measures mechanical hardness by measuring the pressure applied from a diamond tip. With the Knoop scale, corundum has a hardness of 1370 kg/mm2 which is considerably lower than diamond. Because of diamond’s extreme hardness as well as excellent transparency, diamond is extensively used in jewelry and has a variety of industrial uses. But do not fall for the old adage that whatever scratches glass, is diamond.
|The Argyle diamond mine, Western Australia, as it appeared in 1986|
(photo by the GemHunter).
|Absolutely beautiful diamonds (photo courtesy and |
copyright by of Rio Tinto
|A green modified octahedral diamond from |
undisclosed location (photo by the GemHunter)
|Resorbed diamond crystal habits - Argyle diamonds Australia.|
Photo by the GemHunter.
GEM (also referred to as Diamond Detectors, Diamond Detectives) testers (about the size of a pen) are designed to identify the unique thermal conductivity of diamond and distinguish it from other gems and imitations. This one tool can be very useful to a prospector due to the fact that it sells for a reasonable price – and if you think you have raw diamonds, get one of these.
|Grease table. We used a 10:1 mixture of Vaseline |
to paraffin to extract diamonds from concentrates
(photo by W. Dan Hausel).
- Bruton, E. 1979. Diamonds. Radnor, Pennsylvania: Chilton Book Company. 532 p.
- Bundy F.P., and J.S. Kasper, 1967, Hexagonal diamond, a new form of carbon: Journal of Chemical Physics. v. 46, no. 9, p. 3437–3446.
- Dana, E.S. and Ford, W.E., 1951, A textbook of Mineralogy (7th Edition): John Wiley & Sons, New York, 851 p.
- Erlich, E.I., and Hausel, W.D., 2002, Diamond Deposits – Origin, Exploration, and History of Discoveries: Society of Mining Engineers, 374 p.
- Harlow, G.E., 1998, The Nature of Diamonds: Cambridge University Press, 278 p.
- Hausel, W.D., 1998, Diamonds and mantle source rocks in the Wyoming Craton, with a discussion of other US occurrences: Wyoming State Geological Survey Report of Investigations 53, 93 p.
- Hausel, W.D., 2007, Diamond deposits of the North American Craton: Colorado Geological Survey Industrial Minerals Forum, 48 p.
- Hausel, W.D., 2008, Diamond Deposits of the North American Craton in Woods, A., and Lawlor, J., eds, Topics in Wyoming Geology, Wyoming Geological Association Guidebook. p. 103-138.
- Hausel, W.D., 2009, Gems, Minerals and Rocks of Wyoming. A Guide for Rock Hounds, Prospectors & Collectors. Booksurge, 175.
- Hausel, W.D., 2014, A Guide to Finding Gemstones, Gold, Minerals and Rocks: GemHunter publications on Amazon, 368 p.
- Hausel, W.D., and Sutherland, W.M., 2000, Gemstones & Other Unique Minerals & Rocks of Wyoming - A Field Guide for Collectors: Wyoming Geological Survey Bulletin 71, 268 p.
- Lonsdale, K. 1971. Formation of lonsdaleite from single-crystal graphite. American Mineralogist 56:333-336.
- McCallum, M.E., and Mabarak, C.D, 1976., Diamond in State Line kimberlite diatremes, Albany County, Wyoming and Larimer County, Colorado: Geological Survey of Wyoming Report of Investigations 12, 36 p.
- Orlov, Yu.L. 1977. The Mineralogy of Diamond. New York: John Wiley. 233 p.
- Pokhilenko, N.P., Zedgenizov, D.A., Afanasiev, N.P, Rylov, G.M., Milledge, H.J., Jones, A. Hall, A.E., and Reimers, L.F., 2003, Morphology and internal structure of diamonds from the Snap Lake/King Lake kimberlite dyke system, Slave Craton, Canada: 8th International Kimberlite Conference Program w/Abstracts, Victoria, B.C., p. 90-91.