NEW GEMSTONE DISCOVERIES

A 368-page book published in 2014 with color photos, provides insight into the physical characteristics of raw gemstones, listing dozens of GPS coordinates for gemstone deposits in Wyoming, with a few in Colorado and Montana. The book will improve your gem- and rock-hunting skills and take you - 'where no book has taken its readers before'. It provides hints on where gemstones are likely be found and will lead some readers to make discoveries! There is more than enough evidence, that the author did not find everything, and more than enough evidence that many similar deposits remain to be discovered.

As an example, one prospector recovered several diamonds in a gold pan (including one weighing nearly 6 carats) from a creek in Colorado after reading this book (Hausel, 2014). Diamonds were later found by the same prospector in a creek in North Carolina based on the author's work (Hausel, 1998). The diamonds were verified at the University of NC.

There are likely hundreds of deposits yet to be found in Wyoming, Colorado and Montana and Utah. For example, the author describes a potentially large opal, agate and jasper deposit likely located east of Casper, Wyoming (remains unexplored), hundreds of possible diamond deposits based on mineral anomalies in southeastern and southwestern Wyoming extending into Colorado and Utah, dozens of ruby and sapphire deposits based on the presence of mineral anomalies in the Laramie and Wind River mountains, the likelihood of more incredible iolite deposits in the central Laramie Mountains, extensive labradorite (spectrolite) deposits in the Laramie Mountains, many more gold deposits in Colorado, Montana, and Wyoming, the possibility of diamond deposits in Kansas, and much more!

These, and many other gems, are described in the book that will likely lead to more headaches for the BLM (Bureau of Land Management, not the other group of thugs). Those who obtain copies of the book, have a big lead in finding gemstones, minerals and gold! 

The book was released through Amazon and other outlets on October 20th, 2014. As of February 2015, prospectors were making finds in spite of global warming (with temperatures plummeting considerably below zero). Listen to what some and rock hounds reported.

Faceted Wyoming pyrope garnet

(1) One prospector reported recovering 30 diamonds in a creek recommended in the book along with one flawless diamond of 5.92 carats, making it the largest known diamond to have been recovered in this particular drainage basin. The diamonds were verified by a university in North Carolina. Before all is said and done, it is likely tens of thousands of diamonds will be recovered from this region.

(2) Another prospector found several lamprophyres (potential diamond-bearing rocks).

Look at this rounded cobble - how many of these have you walked
over? This one is mostly serpentine, but filled with excellent rounded gem
pyrope garnet and green chrome diopside. It could have diamond. We
found dozens of these south of Laramie Wyoming and north of Ft. Collins,
Colorado sitting on the ground. The rock is garnet peridotite.

(3) Another found rubies, sapphires and gold.

(4) Another reported finding a half-gallon of peridot gemstones!

(5) And yet another prospector found several colored (fire) opals with several precious opals.

(6) And still another (with his daughter), continues finding some of the highest quality labradorite as well as many fabulous pyropes, chromium diopsides, and peridots. 

What are you waiting for, you will never have such a great opportunity again?

You can find more about gemstone hunting searching for the GemHunter's many blogspots and other publications. And if you are interested in prospecting for gold, another book by the author focuses on  gold in Wyoming. Then there are many rich gold deposits in Arizona examined by the GemHunter and published as a book and for Kindle. Then there is gold in Colorado and Montana. 

The cost of the books is relatively high due to the use of color illustrations, but all it takes is one weekend of searching for gold and gemstones using the books with GPS coordinates, and you will be richer by spending time in the outdoors. And if you are lucky enough, you may also find some gems and gold. And the six discoveries mentioned above were made during the winter of 2014 to 2015 after the book was released, so, just imagine the discoveries that will be made in the upcoming seasons.  

Gemstones in the rough found in Colorado by the author. These include 'Cape Ruby' (pyrope garnet)
spessartine garnet, almandine garnet, 'Cape Emerald' (chromian diopside), picroilmenite and chromite.

Did you know that pink diamonds were described in the
Colorado-Wyoming state line district? Some pink diamonds
from Australia have sold for more than $1 million/carat
making them the most valuable commodity on
earth based on weight (photo of fancy colored diamonds
at the Argyle Mine in Australia. Photo by
the Gemhunter)

Can you believe it - someone just found a gold nugget in California that sold for more
than $400,000.  Think there are some in Wyoming?  Most likely.

Iolite cross with white diamonds. The largest iolite
deposits and gemstones in the world were recently
discovered in the central Laramie Mountains north of
Laramie. Both iolite and diamonds were discovered in
Wyoming and there is plenty of evidence that many
more iolite (water sapphire) and diamonds will be found
in Wyoming.

Chromian diopside with topaz cross. Yes, topaz was discovered
in Colorado and beautiful chromian diopside was found at several
locations in Colorado and Wyoming and even in California. Other
deposits will likely be found in Montana and Kansas.

My good friend, the late Dr. J. Dave Love sits on large jade boulders stored in garage.

Billions of carats of labradorite (spectrolite) are likely sitting along Highway 34 in the Laramie anorthosite complex
in the Sybille Canyon area of the Laramie Mountains between Wheatland and Laramie. Yet, few are looking for the gem.

Faceted pyrope garnets in necklace

Wyoming - The Gemstone State

Gem-quality pyrope garnet faceted from rough collected at
Butcherknife Draw near Green River, Wyoming.

Colored gemstones were almost unheard of prior to 1977 other than some fabulous cobbles and boulders of jade, some agates, petrified wood, and a couple of tiny diamonds that required a microscope to see. After I was hired as the Senior Economic Geologist at the Wyoming Geological Survey, I began first to search for diamond deposits, then gold, and along the way, I got interested in gemstones, their geological settings and necessary conditions for formation (chemistry, pressures and temperatures) (Hausel and Sutherland, 2006). It soon became clear that several variety of gemstones should be found in Wyoming but few were ever reported. 

So I went looking and was amazed at all of the gems, diamonds and gold that had been overlooked in the Cowboy State: I kid you not - some sitting right along the highway! And I can guarantee there is a lot more, but it seems like nothing is being done since I left Wyoming in 2007 even though I had found evidence for hundreds of more diamond deposits, gold deposits, a few palladium deposits, several ruby deposits, unbelievable iolite deposits (some specimens of gem iolite as large as Smart Cars), and possibilities for emeralds and other beryl deposits (aquamarine and helidor) to name a few.

Wyoming diamonds from kimberlite, State Line district.

Over the years, I mapped more than 1,000 km2 of complex Precambrian geology along with mapping younger volcanic terrains: it became clear that Wyoming should have a wide variety of gemstones - but, there were few reports of gems found in the State and little evidence that anyone had looked. After I formulated some ideas on what to look for, I soon started making discovery after discovery. Along with these discoveries, some rock hounds were also making interesting discoveries. If only I could have been allowed to continue searching, I would have made many more discoveries.

I found dozens of gemstone deposits and likely the largest colored gemstone deposit on earth. I recovered giant gemstones (one weighing >24,000 carats) and left some in the outcrop that would dwarf my Honda Fit. A few were estimated to weigh >100,000 to >1,000,000 carats and would require jackhammers, backhoes and a dump truck to get them out! Yet these and other giant gemstones remain in situ  all because of one corrupt state geologist and his governor buddy.

I also found evidence for additional ruby and sapphire deposits in the central Laramie Range, Granite Mountains, Owl Creek Mountains and southern Wind River Mountains after finding seven previously unknown ruby deposits. And I began chasing more opal deposits where ever the countryside had been blanketed by Tertiary to Recent ash falls from past eruptions from the Yellowstone caldera (I had already found one of the largest opals on earth that weighed more than 77,000 carats with larger stones left in the field and also found a large deposit of fire opal). I was searching for other gems including possibilities of emeralds in the Sierra Madre and Overthrust belt, investigating enormous amounts of sky blue kyanite, looking for more iolites, rubies, sapphires and aquamarines, and I had verified Colorado, Montana and Wyoming was underlain by a major diamond province that to this day (2022), remains only partially explored.

Gem kyanite from Laramie
Range

It was clear, due to the unusual geology of Wyoming being a craton that was underlain by (1) very old Archean rocks (rocks greater than 2.5 billion years in age) that were subjected to very high pressures and temperatures resulting in their recrystallization and (2) some younger Proterozoic (2.5 billion to 600 million years in age) schists

and granites that had a wide variety of mineralogy and chemistry that were also subjected to high pressures and temperatures, (3) younger Phanerozoic (less than 600 million years old) sedimentary rocks, (4) Tertiary and Quaternary volcanic rocks and ash falls and (5) rare kimberlites, lamproites and lamprophyres (subjected to extreme pressures), that provide favorable host rocks for a large variety of gemstones – but no one had bothered to look.

I began to search for different gemstones keeping in mind geological environments and rock chemistry. I started to make lists of what I might find and kept extensive files on various gemstones and their geological environments, worldwide. While mapping, I was also searching for gold, base metals, strategic metals, gemstones and decorative rocks. Soon I was finding many gemstones on my list. Here is the list of what I started searching for and finding in many cases:

Giant jade boulder from Jeffrey City, Wyoming.

Agate, aquamarine, almandine, andalusite, andradite, amethyst, apatite, azurite, ammolite, apache tears, amber, ametrine, barite, bloodstone, blue chalcedony, bronzite, burgundy diamond, canary diamond, carnelian, chalcopyrite, champagne diamond, cherry opal, chocolate diamond, chromian diopside, chromian enstatite, chrysoberyl, chrysocola, chrysoprase, citrine, common opal, clinozoisite, cuprite, platinum, palladium, drusy quartz, emerald, epidote, fire (mexican) opal, fluorite, fuchsite, garnet, gold, golden beryl, golden sapphire, goshenite, green aventurine, green tourmaline, heliodor, hiddenite, idocrase, iolite, jade, jade pseudomorphs, jasper, jasperoid, jasper breccia, kunzite, kyanite, labradorite, lemon serpentine, lepidolite, malachite, maxixe, black opal, moonstone, morganite, moss agate, onyx, oriental sapphire, peridot, pink diamond, pink sapphire, precious opal, prehnite, pyrite, pyrope, quartz, rock crystal, rose diamond, rose quartz, rubellite (pink tourmaline), ruby, rutilated quartz, rutile, schorl, specular hematite, scapolite, sillimanite, silver,  smoky quartz, sodalite, spessartine, sphene, sphalerite, spodumene, star sapphire, tanzanite, tourmaline, tigerseye, varisite, white sapphire, zoisite and zircon.

A 12-carat, nearly flawless, rough pink sapphire recovered from the Palmer
Canyon deposit by Vic Norris.

The more I searched, the more I found. I spent time educating (and vise versa) rock hounds, prospectors, companies, geologists and mineral collectors in Wyoming and nearby states by providing lectures, short courses and field trips on how, where and what to prospect for. I also wrote many articles and books on prospecting. Soon I was not the only person looking for gemstones. Others began searching and finding gems in the Cowboy State. Over 3 decades, I found nearly 75% of the gemstones on my list and I suspect if I would have been able to continue, I would have found many more deposits and possibly as many as 85 to 90% of the gems.

Flawless pyrope garnet I collected at Butcherknife
Draw, Wyoming and sent to Sri Lanka for faceting.

I was asked to participate in several conferences with people showing up to my lectures carrying all kinds of minerals and rocks previously unreported in Wyoming, including materials like gem-quality labradorite found by Norma Beers (RIP) in road bed material from Albany County 11 and 12 where I had recently found a breccia pipe with limestone xenoliths adjacent to a significant kimberlitic mineral indicator anomaly that we had identified prior to 1988. Others found diamonds in anthills in the Green River Basin, and a few showed up with beautiful gold nugget specimens  (one person had more than a hundred high-quality nuggets from South Pass. Others showed me ball jars full of gold nuggets and dust from the same region, along with fantastic specimens of jasper, agate, and even an emerald still in country rock.

I had found many previously unreported kimberlites and kimberlitic indicator mineral anomalies in the Iron Mountain district near Chugwater and this attracted prospectors to dig for diamonds. I visited the Great Diamond Hoax site in northwestern Colorado where I recovered diamonds, rubies, and pyrope garnets salted by scam artists in 1872. But then I was told by Dr. Tom McCandless that Diamond Peak actually had conglomerate containing gem-quality pyrope garnet and chromian diopside (both diamond indicator minerals). What was the chance of this happening? 

Diamond companies started to show up in Colorado, Montana and Wyoming. And the Kelsey Lake diamond mine opened on the border south of Laramie - but closed 6 months later due to legal problems. Other companies picked up properties in the same region and found enough diamonds for commercial production. 

But, between 2004 to 2006, the Wyoming Geological Survey was decimated by a sociopath working for a democrat governor. For ethical and health reasons, I decided to take early retirement and run US exploration for DiamonEx Ltd, an Australian Mining Company with interests in Botswana. And I had a wonderful time until the market crash of 2008, which put many mining companies out of business.

Gem kyanite cut into cabochons from Palmer Canyon, Wyoming.
There are literally hundreds of billions of carats of this gemstone
in eastern Wyoming at Palmer Canyon, Cooney Hills, Grizzly
Creek and likely in other areas of the state (Hausel, 2009). These and other
aluminum-rich minerals are often found in what geologists call metapelite
(mica-rich schists) that was subjected to moderately high pressures and
temperatures. Using this information, I found dozens of these deposits around
Wyoming. The colors and fractures in these gems actually enhance their
appearance. I am very surprised that someone has not tried to market these
as they are relatively easy to cut. They are a low value gem, but when there
are billions of carats - who cares.

While at the Wyoming Geological Survey on the University of Wyoming campus, I had received regional and national awards for communication skills including the American Association of Petroleum Geologists President's Certificate and the Wyoming Geological Association's Distinguish Service Award for my research on Wyoming's geology and for the dozens of talks I had presented at that society. I had also been twice nominated for the Dibble Mapping Award by two former directors of the Wyoming Geological Survey - Gary Glass and Dr. D.L. Blackstone, Jr. The Laramie Lyceum had presented me Distinguished Speaker of 1994 and the University of Wyoming Department of Geology & Geophysics included me as Distinguished Lecturer and these were just some of the national and international recognition I had received over the years for being a great communicator. When I was in college at the University of Utah, I had been employed as an astronomy lecturer at the Hansen Planetarium because of communication skills. But what the heck, what did all of these people know including Who's Who in America, Who's Who in Science, Who's Who in the World, 2000 Notable American Men, etc.

I was considered to be one of the few specialists in Archean gold deposits, diamond deposits, colored gemstone deposits, greenstone belts and more. I was told by the chairman of the Geology Department at UW, that it was only because of my work and research that geologists had a good grasp of the Precambrian Geology. I had been awarded and inducted into two different Halls-of-Fame (nominated for a third) for my geological research, education efforts and communication skills, something that I suspect no other geologist in Wyoming (and possibly the US) could claim.

Giant ruby found in the Granite Mountains. This was at one time the
largest ruby ever found on earth - but unfortunately, much of the ruby
(purple red) was replaced by zoisite, clinozoiste, fuchsite (green matrix).
However, it suggests that exploration of this deposit will
potentially result in discovery of some of the largest rubies on earth.

I was one of seven geologists who  had found one of the largest gold deposits in North America, found a whole new gold district, studied hydrothermal alteration characteristics associated with a large disseminated gold and copper deposit, identified more than a hundred gold anomalies, dozens of gemstone deposits, a couple of massive sulfide deposits, one of the few nickel anomalies in Wyoming. I mapped nearly every mining district in Wyoming along with the two largest kimberlite fields in the US and the largest lamproite field in North America. 

It was time to move on, so I went to work as VP of US Exploration for DiamonEx Ltd, where I found some diamond bearing kimberlites, identified several hundred possible kimberlites for the company to explore and drill.  After DiamonEx, Ltd, I worked as a consultant for other mining companies including Black Range Resources, Giant King Gold, Strathmore Resources, Wyoming Gold, Saratoga Gold and others. Personally, I love geology and I love hunting for new mineral deposits.

Transparent blue barite from Shirley Basin, Wyoming.

Cape Emerald from State Line district, Wyoming

Banded Jasper from Tin Cup district, Wyoming

1.1 carat faceted ruby from Palmer
Canyon, Wyoming

Enormous ruby faceted from rough collected in the Laramie
Range, Wyoming

Cabochon of specularite with copper from Charter Oak mine,
Wyoming

Gem labradorite from Sybille Canyon,
Wyoming.

Malachite with specular hematite from the Hartville area, Wyoming

Geology of Gemstone Deposits

Large chlorite pseudomorph after garnet found in the Sierra Madre Mountains, Wyoming. The chlorite slowly replaced the garnet and accepted the garnet's crystal form. 

Much of Wyoming is underlain by Archean cratonic basement rocks and cratonized Proterozoic rocks that provide favorable geological environments for a variety of gemstones – notably diamond, iolite, ruby, sapphire, garnet, kyanite, andalusite, sillimanite, labradorite, jewelry grade gold, platinum and palladium nuggets, emerald, aquamarine, helidor, tourmaline, spinel, clinozoisite, zoisite, apatite, jasper, specularite, etc. Thick Phanerozoic sedimentary rock successions with lesser Tertiary volcanic rock cover large portions of the basement terrain. Some of these Phanerozoic rocks provide favorable hosts for other gemstones including opal, placer diamond, placer gold, placer platinum, placer ruby, jasper, agate, emerald, varisite, etc.

Using traditional exploration and prospecting methods, dozens of gem and precious metal deposits were discovered over the past 3 decades, including major discoveries and geological and mineralogical evidence for significant undiscovered deposits. Major swarms of mantle-derived kimberlite, lamproite, and lamprophyre, many of which have proven to be diamondiferous, also host colored gemstones including pyrope garnet (Cape Ruby), spessartine garnet, almandine garnet, chromian diopside (Cape Emerald) and chromian enstatite. One lamproite also yielded peridot.

Favorable conditions for crystallization of metamorphogenic gemstones during regional amphibolite-grade metamorphism occurred during the Precambrian. In this terrain, metapelite in the central Laramie Range hosts kyanite, sillimanite and andalusite. These three minerals provide evidence of favorable pressures and temperatures needed for crystallization of aluminous gemstones including ruby, sapphire and kyanite. Cordierite (iolite) another aluminum-rich gemstone, formed during a later thermal event. This later event was responsible for deposition of world-class iolite (Water Sapphire) gemstone deposits.

While searching for gold, I came along
this giant jasper deposit.

Evidence for undiscovered gemstone deposits is predicted based on mineralogical anomalies detected during various research projects from 1977 until 2005. These include ruby, sapphire, gold and aquamarine found in stream sediment samples as well as favorable geological terrains that remain unexplored. Other anomalies include pyrope garnet (several with G10 geochemistry), picroilmenite, and some chromian diopside that provide evidence for hundreds of undiscovered diamond deposits. Elsewhere, detrital diamonds reported by various prospectors provide direct evidence for undiscovered diamond deposits. Other geological and mineralogical evidence suggest the presence of additional undiscovered opal, cordierite (iolite) and kyanite deposits. Wyoming could potentially become a major source for gemstones including diamond, gold, platinum, palladium, Cape ruby, Cape emerald, iolite and opal.

Giant chrome diopside gem in kimberlite from Colorado.

DIAMONDS, DIAMONDS & MORE DIAMONDS

Gem diamonds from Kelsey Lake Colorado.

My first experience in diamond hunting occurred back when I mapped the Wyoming State Line kimberlite district. I  later mapped the Iron Mountain and Sheep Rock kimberlite districts and the Leucite Hills lamproite field. And when I had time, I  explored for diamonds as a consultant for US, Australian, and some Canadian companies. 

I searched for kimberlite, lamproite and lamprophrye in California, Kansas, Montana & Wyoming & identified, a few hundred cryptovolcanic structures within & surrounding the State Line in Colorado and Wyoming - some of which are likely diamond deposits (nearly all remain unexplored)! A few  include Indian Guide, Twin Mountain, Happy Jack & others. I expanded my research & found cyptovolcanic structures in Canada & even in the Kimberley region of South Africa, and found a major anomaly of 50+ anomalies sitting along Interstate-80 in Wyoming!

16.8 faceted gem diamond, Kelsey Lake, Colorado

Diamond deposits south of Laramie are in kimberlite pipes & placers. The kimberlites are deeply eroded & spilled millions of diamonds into the surrounding streams, but no one ever systematically looked for diamond in the creeks (even so, diamonds were accidentally recovered in Rabbit Creek along with a 5-carat diamond, and hundreds were recovered in George Creek, and several including a 6.2 carat diamond were recovered in Fish Creek, but the rest of the streams are mostly UNPROSPECTED!

Kimberlite is a ultrabasic, potassic igneous rock that erupts along fractures from 90- to 120-mi depths. They typically occur in very old cratons & cratonized rocks (basically ancient continental cores that consist of >1.5 billion year old granite, gneiss & schist). The magma, under pressure rises rapidly from the mantle because of the great depth & because of considerable water vapor & carbon dioxide under pressure. Some suggest gaseous emplacement velocities of kimberlite are on the order of Mach 3. The eruption is relatively cool: CO2 gas expands cooling the magma such that emplacement temperatures of 32 degree F are not uncommon. This collection of unusual characteristics results in small, circular maar-like volcanoes (without cones) & dikes that are structurally controlled.

Gem diamond with excellent characteristic
trigons on surface

Things to keep in mind: kimberlite will serpentinize because of water vapor, this produces a relatively soft rock that erodes faster than surrounding country rocks & usually results in a depression with different vegetation than the surrounding rocks. These depressions may contain shallow ponds. They are structurally-controlled such that >one anomaly is often found in a line. Because of calcium carbonate in kimberlite, carbonate will leach out into the pond staining the soil white. Keep in mind that salts are not all that uncommon in basins where lots of young sedimentary rocks occur with considerable carbonate. But in the craton basement (i.e., mountain ranges of Wyoming) there is no known source for carbonate, so if you spot a structurally-controlled lake surrounded by salt in old Precambrian rock, you might want to find out why? When you find one, typically, you will find others along the same structure.

Diamonds found in Colorado & Wyoming ranged from microdiamonds to 28.3-cts & included one chip from a 80- to 90-carat stone. Many people erroneously assume there are no commercial diamond deposits in this region - but all four diamond mills that were constructed in the district, were so poorly designed that they likely rejected as many diamonds as they recovered. Even so, commercial diamond deposits were encountered at Kelsey Lake and mined for only about 6-months before lawsuits shut down the operation. Thus, only the very top of the diamond pipe was touched by mining and thousands (if not many millions) of gem-quality diamonds lie in the host kimberlite and remain unmined!  And this doesn't even include the thousands of placer diamonds eroded from the kimberlite and carried downstream over geological time. 

A flawless, 14.2-carat octahedral diamond recovered from
the Kelsey Lake diamond mine. Photo courtesy of Howard
Coopersmith.

Then there is the Sloan 1 and 2 kimberlites in Colorado. DiamonEx from Australia was developing this property for commercial tests when the economy crashed in 2008 and put most diamond operations out of business including DiamonEx Ltd. Up to that point, the property appeared to be commercial based on the diamond ore grades.

All of the mills in the State Line district were so poorly designed they rejected diamonds of all sizes. The Kelsey Lake mill rejected anything weighing >40 cts! It also rejected many diamonds under 40-cts such that when the tailings were tested in 1997, the first sample yielded a 6.2-ct gemstone along with other diamonds!

High wall of Kelsey Lake kimberlite, State Line district, Colorado-Wyoming. Nearly all of the 
diamondiferous kimberlite was abandoned and never mined because of lawsuits. To this day (2022) 
this diamond deposit remains mostly unmined.

The grades of several kimberlites were high, the gem:industrial ratios were good & diamond values were reasonable. The biggest problem with the State Line district was that diamond mill expertise was in short supply.

CAPE RUBIES, CAPE EMERALDS, GARNETS

Diamonds were discovered in Wyoming & Colorado in 1975 by Mac McCallum, Chuck Mabarak & the USGS. This lead to some exploration for diamonds. Associated with diamonds are a host of extremely rare mantle nodules & gemstones known as Cape Ruby (pyrope garnet), Cape Emerald (chromian diopside & enstatite) that are always overlooked by mining companies. Yet these are very attractive, value-added gemstones. With some marketing skills, could potentially capture large parts of the colored gemstone market. For example, many Cape Emeralds are much more saturated & beautiful than emerald.

These gems were found by many prospectors and geologists all over Wyoming & northern Colorado. Large areas in the Green River & Bighorn Basin contain these diamond indicator minerals, yet little exploration has ever occurred for these or their source rocks.

Photos - Diamond indicator minerals from Sloan kimberlite, Colorado, & faceted pyropes from Green River Basin, Wyoming & Kyanite Eclogite from the Aultman 2 kimberlite, Wyoming.

OPAL

Resistant, opal, boulder adjacent to rock hammer in Tertiary
volcaniclastics, with a seam of resistant opal lying beneath the
 boulder and hammer, Cedar Rim, Wyoming.

A rockhound from Riverton, Wyoming, mentioned opal was reported south of town near Cedar Rim at one of my rock hound club talks. When I returned to Laramie, I began searching old US Geological Survey reports on the stratigraphy of the area and found, in passing, mention of opalized rock in some of the stratigraphic columns - so, I headed to the area not knowing what I might find, but the reports left me with the impression that these were just trace amounts. So, when I arrived at Cedar Rim, I was absolutely amazed at the extent of the opal. The great majority of the material I classified as common opal, but also found an entire hillside with colorful red-orange, orange to yellow Mexican opal, and Mexican opal breccia, and traces of precious opal, along with dendritic agate (Sweetwater agate) and a host of colored agates. Based on the presence of the precious opal, I suspect some seams might be found at depth. After spending a few days in the opal field, I later found additional US Geological Survey reports describing some opalized tuffaceous sediments located to the west and east of Highway 135 suggesting that there is likely more opal to the west of the Cedar Rim deposit.

Specimen of 'Candy' opal from Cedar Rim - a mix of white
common opal with colored 'Mexican' opal.

The Cedar Rim deposit lies east of highway 135 and is cut by oil field roads. A few old geological reports from 50 t0 80 years ago mention opal in passing, so I was surprised to find opal scattered over 14 mi2, opal masses containing 80,000-carats along the edge of the oil field roads, and common, fire & precious opal and scattered Sweetwater agate, along with some of the nicest decorative stone in Wyoming. All occurring in Tertiary-age volcaniclastic sedimentary rocks that had a notable

contribution of volcanic ash erupted from Yellowstone in the past.

Cedar Rim boulder opal. All of the boulders and
cobbles that stand out as resistant rock, is typically
filled with opal.

This gave me a clue - nearly all of Wyoming was blanketed by volcanic ash (as was Nebraska and South Dakota). Guess what? There are other opal fields waiting to be discovered. So I found millions of carats of common & fire opal & traces of precious opal (including black opal) that suggest as soon as someone digs, valuable veins of precious opal will be found as depth!

The waxy material in the rock matrix is common opal. 

PERIDOT

In 1997, I decided to search the Leucite Hills in western Wyoming for diamonds (see photo at left). I didn't find diamonds, but mark my words - "DIAMONDS WILL BE FOUND HERE". This is an easy prediction to make based on geology.

The Leucite Hills consist of several lamproite volcanoes & flows that erupted 900,000 to 3.1 million years ago. They started their journey under one of the thickest parts of the Wyoming Craton. Cratons are very old, cool, continental cores necessary to have melting deep within the earth's upper mantle (where diamonds are formed). While exploring this region, I collected grab samples from lamproite in the northeastern part of the field & two yielded chromites with similar geochemistry to chromites found as mineral inclusions in diamond - thus this tells me some of the volcanoes began their journey at 90 to 120 miles beneath the surface where diamonds are common.

Diamondiferous lamproites are found at Murfreesburo, Arkansas; Argyle & Ellendale, Australia; Majhgwan-Chelima, India; Kapamba, Zambia; Aldan, Russia & Bobi, Ivory Coast. The richest deposits are typically found in olivine lamproites which often alter to serpentinite (a very soft material) that erodes quickly, thus such deposits are usually hidden within a field of leucite lamproites (which are much harder rock). Thus, this all suggests a few diamonds are likely to occur in the lamproites with diamond-stability chromites, but the locations for rich diamond deposits are hidden. Along the northern edge of this field, a large sand dune field that marks the location of a major continental shear - a favorable structure for hidden lamproites. One can almost guarantee there are diamondiferous olivine lamproites in this area hidden under a few feet of sand. Lamproites are also well known for colored stones - brown, yellow & the beautiful, extremely rare Argyle 'Pinks'. Some have sold for >$US1 million/carat!

While searching for diamonds, I started looking for olivine. In 1997, I came across two green anthills at Black Rock - the ants had collected all of the available olivine in the immediate area & decorated their hills. So I collected the hills & processed them for diamonds - but all we found were 13,000 carats of flawless peridot (gem-quality olivine). Some were 12 millimeters in length. I also found peridot in place that were nearly 0.5 inch across.
Even though olivine had been recognized in this area >100 years ago, no one had ever looked at the quality of the olivine. Later, I mapped the Leucite Hills and identified all of the olivine bearing volcanoes.

GEMSTONES & GEOLOGY

A good understanding of geology, persistence, & luck can lead to incredible treasures. In 1977, I started work as a research geologist at the Wyoming Geological Survey in Laramie. Next to nothing was known about gemstones in the state, but over the years, I tracked down many mineral deposits & found some of the largest gemstone deposits ever found on earth. Anyone can do it. 

My story is found in many publications and blogspots, the most recent available at Amazon, the Wyoming Geological Survey publications office and the University of Wyoming bookstore in Laramie, as well as at your local bookstore.

Some of the many gemstones discovered in Wyoming since 1977.