|The GemHunter searching for gold and diamonds in the Douglas Creek district of Wyoming|
I spent years in Wyoming working on the University of Wyoming campus. For vacations, I worked for various companies searching for mineral deposits around North America. I left only because the director turned out to be as crooked as any politician could be and violated everyone's rights to free speech, and much more. And no one in Wyoming at the time cared that this person drove away half of the staff (three died) and advisory board, and should have been investigated for many things, including having a low IQ,
|Award for a giant gold discovery in Alaska|
But, since I am familiar with Wyoming, let's first talk about the land of Cowboys and Cowgirls. Wyoming has a large variety of minerals and rocks and was a place where new discoveries were made every year from 1977 to 2006. But since 2006, its been quiet. Why?
For instance, diamonds were accidentally discovered in 1975 south of Laramie - but these were tiny micro-diamonds of little significance and required a microscope to see them. Since the accidental discovery of diamonds in a Wyoming kimberlite, many similar deposits were found in Colorado, Kansas, Michigan, Montana and Wyoming, and some of the richest diamond deposits in the world were found in Canada by some of the early Colorado and Wyoming diamond explorers. In Arkansas, diamonds were already known to occur in a olivine lamproite at the Crater of Diamonds State Park.
Using traditional prospecting methods to search for other diamond deposits, some companies and the WGS identified hundreds of mineral anomalies. Such anomalies are typically found by panning for diamond-indicator minerals: rare gemmy minerals caught up in rare volcanic eruptions that accidentally trapped diamond-bearing rock at depths of 90 to 120 miles or more, and carried it to the surface of the earth. One of the more prominent diamond-bearing volcanic rocks is known as kimberlite. Such rocks were identified in South Africa and named after the Kimberly region. Kimberlite is now known as the principal host rock for commercial diamond deposits.
So, while you are prospecting, as soon as you find some kimberlitic indicator minerals by panning in streams or in anthills, you should simply follow the anomaly upstream or upslope until you run out of indicator minerals. At that point, look for some kind of anomaly that may be a depression, a vegetation anomaly, etc. While mapping and prospecting in known kimberlite and diamond fields (such as Iron Mountain, Middle Sybille Creek, State Line and elsewhere), I found a couple of kimberlites by searching depressions, vegetation anomalies, carbonate rich blue ground soils (reacts to weak hydrochloric acid) in granitic and gneissic terrains, geophysical anomalies, and by following structural alignments of known kimberlites.
Following alignments is one of the easier ways to find previously unrecognized kimberlites. Kimberlites erupt along linear fractures and at certain points along these fractures, they reached the surface. So, if you can figure out the direction of this lineament, just follow the compass direction keeping your eyes open for something out of place.
|Distinct depression near the Kelsey Lake diamond mine in |
Colorado. There is also a vegetation anomaly associated with
this kimberlite pipe (higher stands of grass) known as the
Many of the diamond discoveries in North America (with the exception of the Arkansas pipe) can be attributed to the optimism expressed by Dr. Daniel N. Miller (RIP), who was the State Geologist and Director of the Wyoming Geological Survey (WGS) at the University of Wyoming. Dr. Miller along with a couple of prospectors named Frank Yaussi, and Paul Boden, were about the only people who felt there were possibilities that some kimberlite pipes in Wyoming and Colorado had more than just micro-diamonds.
While searching for gold in Colorado near the Sloan diamond-rich kimberlites, Frank found many diamonds in his gold sluice, but no one at Colorado State University or the University of Wyoming would give him the time of day - they just ignored him (Frank Yaussi, personal communication, 1980). Then Paul Boden from Saratoga, Wyoming found a couple of excellent octahedral diamonds in the Medicine Bow Mountains: again, no one at the University of Wyoming showed any interest (Paul Boden, personal communication, 1977).
|The Boden diamonds from the Medicine Bow|
But Dr. Dan Miller was optimistic and jump-started the diamond industry in North America. He provided some funding to his Minerals Section at the WGS to begin to evaluate the Wyoming deposits, and soon attracted me to his staff, along with two mining companies - Cominco American and Superior Minerals to search for diamonds in the Colorado-Wyoming State Line district. Superior Minerals, with company CEO, Hugo Dummet, tested for diamonds at the Sloan 1 and 2 kimberlites in Colorado, while Cominco tested some Wyoming kimberlites after building a diamond mill in Fort Collins. Years later, Hugo was appointed head of BHP and invested in the great Ekati diamond deposit in Canada, with its 156 diamondiferous kimberlite pipes! After the Ekati discovery, many other diamond deposits were found in Canada - but US exploration, more or less died and most everyone overlooked the Kelsey Lake kimberlites in Colorado.
|Sample of Chicken Park kimberlite, Colorado|
Gold in the Rattlesnake Hills, Wyoming
What makes this area so significant is the presence of a Archean greenstone belt fragment. 'Greenstone belts' have been equated to 'Gold belts' in some cratons in the world, such as those in Africa, Australia and Canada. Greenstone belt rocks are mostly anomalous in gold; thus, if there is a way to mobilize the gold by hot hydrothermal fluids and geological methods for concentrating the precious metal in chemically favorable rocks or traps (ore shoots) developed during structural deformation, there is a possibility of forming significant to major gold deposits. So, here we have part of an exposed greenstone belt in the Rattlesnake Hills that is more than 2.5 billion years old. It's been intruded by several, much younger, Tertiary age (65 to 2.6 million years old) igneous intrusives that provided heat and mobilized gold and fluids from the intruded rocks. The belt is highly fragmented by deformation during the Laramide orogeny, so, all of the necessary requirements for a major gold deposit are there. I put these ideas together in 1981 after sampling another significant gold deposit in the Seminoe Mountains greenstone belt earlier in 1981 where a found some specimens with visible gold, received some highly anomalous assays including a mine dump sample that assayed 2.87 opt Au, and a banded iron formation sample with more than 1.0 opt Au. This area in the Seminoe Mountains also had distinct alteration zones from hydrothermal fluids. It is hard to believe, but I found most of these deposits and dozens of other gold anomalies prior to 1985 with an assay budget of only $100/year! As a comparison, mining companies typically spend hundreds of thousands and even millions of dollars on sampling, assaying, and drilling. Just take a look at Oak Island - and that's not even a mining company. And the company that the WGS originally contracted for assays, typically charged about $30/sample. Its a miracle I found anything.
Several other discoveries were made by the WGS during mapping projects in the historic mining districts at South Pass (Hausel, 1991), Seminoe Mountains (Hausel, 1994), Sierra Madre (Hausel, 1986), Laramie Mountains (Hausel and Hausel, 2011) and Medicine Bow Mountains (Hausel, 1989, 1993). In addition to these lode discoveries, prospectors and treasure hunters found many gold nuggets with metal detectors. For example, a 7.5 ounce nugget was found at South Pass by a Wyoming prospector. Another treasure hunter from Ft. Collins found more than 100 nuggets at South Pass, and a prospector from Arizona recovered 399 nuggets in the Sierra Madre (Hausel and Sutherland, 2000).
|A 7.5 ounce gold nugget found by prospector at|
Besides gold and diamonds, other metals and gemstones occur in Wyoming. In 1995, a significant platinum, palladium and nickel anomaly with associated copper silver, gold and silver in the Puzzler Hill area of the Sierra Madre near Saratoga (Hausel, 1997; 2000).
|pyrope garnets and emerald-green chromian diopsides from|
Butcherknife Draw, Wyoming
Another attractive gemstone discovered in 1998 in Wyoming is referred to as iolite, also known as cordierite and water sapphire. This led to a world-class discovery, first with spectacular iolites I found at Palmer Canyon, then with some iolite gemstones that potentially weigh more than a ton, at Grizzly Creek. But then I was able to find gem-quality iolite also at the Sherman Hills in the Laramie Mountains. This latter site is mostly unexplored, but based on trenching of cordierite around world war II, this latter Sherman Hills-Raggedtop deposit could host more than a trillion carats of the gemstone! The gem, known as iolite (gem-quality cordierite), is transparent, violet to deep blue (Hausel and Sutherland, 2000; Hausel, 2014). I found the easiest way to search for iolite is to look for areas that contain aluminum-rich (amphibolite-grade) metamorphic rocks such as kyanite schists, cordierite schists and andalusite schists and then start looking for some attractive glassy gemstones that are blue to purple in color.
|Rhodolite (pyrope garnet) faceted from rough material I|
collected in the Green River Basin of Wyoming.
|Youngite agate breccia|
|Blue forest agate (courtesy of Wayne Sutherland|
|Copper ore, Ferris-Haggarty mine|
|Schematic cross-section of|
a classical kimberlite pipe and
feeder dike complex
|Kelsey Lake diamond mine - photo by W. Dan Hausel|
|Wyoming jade (nephrite) with quartz crystals|
|Gold from South Pass. Photo by W. Dan Hausel|
|The author (GemHunter) stands in middle of photo at the base of Zirkel Mesa in the Leucite Hills|
wearing white field hat.
|Gold from Douglas Creek, photo by W. Dan Hausel|