|Kelsey Lake diamond mine highwall, Colorado|
By 1839, the Brazilian diamonds were thought to have been found in situ in the Minas Gerais region of Brazil in a rock called "itacolumite", a micaceous sandstone with interlocking quartz grains. Because of this discovery, itacolumite was considered as the primary host for diamond. This source was so ingrained in the thinking of people in the 1800s, that following the discovery of diamonds in placers in South Africa, a well-known jeweler from London pronounced the South African diamond discoveries to be fraudulent, as no rock resembling itacolumite had been found in the area.
|Molly Lake - example of a pan (depression) often found over|
|Blue ground (muddy diamond-bearing clay) at the Schaffer complex kimberlite, Wyoming exposed in a dozer trench in|
1979. The blue ground is a montmorillonite clay - or a 'calcareous talcose soil' formed from decomposed kimberlite.
|Asbury Harpending, a Kentucky gentleman.|
|Rough diamonds from undisclosed locations.|
|Henry Janin, Mining Engineer|
|Map showing the Location of the Great Diamond Hoax (after Hausel and Stahl, 1995).|
|The GemHunter, aka Dan Hausel, shows prospectors diamond indicator|
minerals in anthills in the Green River Basin of Wyoming.
|Outcrop of Bishop Conglomerate at|
Cedar Mountain, Wyoming
|Sample of Bishop Conglomerate with chromian diopside|
When the group returned to New York, Janin made his stating they had recovered 824 carats of diamonds, 7,200 carats (4 pounds) of rubies in just four working days, from 3,000 pounds of gravel. It was also reported that the property covered at least 3,000 acres of ground, although Janin had only sampled a small portion of a 160 acre block. Janin was so taken in by the fraud it was suggested that there were enough rubies and diamonds in a single gulch to purchase the entire city of New York.
|Some of the many pyrope garnets and chromian diopsides|
collected at Cedar Mountain.
|Hey, I thought I saw these guys in the Cowboy Bar in Laramie. Well, actually|
this is an old photo of the 40th Parallel Survey including Clarence
King (far right).
Coincidence. The location of the Great Diamond Hoax was right on the edge of an Archean Craton! Today, cratons are considered excellent terrains to search for diamondiferous kimberlite, lamproite and lamprophyre. But in 1872, this relationship was unknown. Nearly 100 years later, in 1975, diamonds were found in kimberlite only 175 miles east of the great diamond hoax site and diamonds were also found in lamprophyre 55 miles west of the great diamond hoax site - all a coincidence. In addition, hundreds of diamond indicator mineral anomalies have been identified throughout this region. This region along the edge of the Wyoming Craton is considered to have high potential for discovery of gem quality diamonds in kimberlite.
So - how do you identify a rough diamond? Its not as difficult as you think - read my blog about diamonds.
- Hausel, W.D., and Stahl, Sandy, 1995, The great diamond hoax of 1872 (abstract): Pacific Northwest Mining and Metallurgy Conference, Bellevue, WA., p. 15.
- Hausel, W.D., 1995, Diamond, kimberlite, lamproite, and related rocks in the United States: Exploration and Mining Geology, v. 4, no. 3, p. 243-270.
- Hausel, W.D., 1995, Diamonds and their host rocks in the United States: Mining Engineering, v. 47, no. 8, p. 723-732.
- Hausel, W.D., and Stahl, Sandy, 1995, The great diamond hoax of 1872: Wyoming Geological Association Guidebook, p. 13-27.
- Hausel, W.D., Sutherland, W.M., and Gregory, R.W., 1995, Lamproites, diamond indicator minerals, and related anomalies in the Green River Basin, Wyoming: Wyoming Geological Association Wyoming Guidebook, p. 137-151.
- Hausel, W.D., Love, C.M., and Sutherland, W.M., 1995, Field Guide to the geology and volcanology to the Leucite Hills, Green River Basin, Wyoming: Wyoming Geological Association Road Logs to the, p. 45-53.
- Hausel, W.D., Marlatt, G., Neilsen, E., Gregory, R.W., 1995, Geology and hydrothermal alteration of the Quaking Asp silicified zone, Green River Basin, Wyoming: Wyoming Geological Association Guidebook, p. 125-136.