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I love searching for diamonds. My first chance to explore for diamonds deposits occurred in 1977 when I was hired by Dr. Dan Miller of the WGS to appraise the newly discovered district south of Laramie. I ended up mapping the State Line district, found 9 diamond-bearing kimberlites my first 2 years & later mapped the Iron Mountain & Sheep Rock districts and the Leucite Hills lamproite field and explored for diamonds for some US companies, an Australian company and some Canadian companies. In fact, I was promoted to US Exploration Manager and later VP of DiamonEx USA for DiamondEx Ltd (see GEMHUNTER).

I found lamprophryes in Montana & Wyoming & identified several hundred cryptovolcanic structures within & surrounding the State Line that are likely diamond deposits (these remain unexplored). A few of these include Indian Guide, Twin Mountain, Happy Jack & others. I expanded my research & found similar cyptovolcanic structures in Canada & even in the Kimberley region of South Africa. I found a major district of 50+ anomalies sitting along the interstate in the US!

Photos – Above, gem diamonds from Kelsey Lake, Colorado, vegetation anomaly over kimberlite at Iron Mountain, and exposed blue ground in highwall at Kelsey Lake. Below, 14.2 ct flawless octahedron from Kelsey Lake, aerial photo over the Ekati diamond mine in Canada (one of 5 major mines developed in Canada since 1998), carbonate-stained soil over cryptovolcanic structure, and view of one of the Lost Lakes cryptovolcanic structures.

 Commercial deposits occur in placers, kimberlite and/or lamproite & I’ll bet other commercial deposits will be found in lamprophryre in the future. The diamond deposits south of Laramie were in kimberlite & placers. The kimberlites are deeply eroded & spilled millions of diamonds into the surrounding streams, but no one has ever systematically looked for diamond in the creeks (even so, diamonds were accidentally recovered in Rabbit Creek 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 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? And if you find one, typically, with effort, 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-ct stone. Some believe there are no commerical deposits in this area, but all mills were so poorly designed they rejected all diamonds of any size. For example, the Kelsey Lake mill rejected anything weighing >40 cts! It also rejected most diamonds under 40 cts such that when the tailings were tested in 1997, the first sample yielded a 6.2-ct stone! 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 good diamond companies with diamond expertise were in short supply.


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.


Little was known about gold in Wyoming, thus I set out to map, evaluate & find more. I discovered gold everywhere I looked. I was amazed at how much had been overlooked. I published compendiums that are used by prospectors & geologists & mapped several mining districts that were previously unmapped or only partially mapped. I even found a previously unrecognized ultramafic massif with significant palladium, nickel gold & copper mineralization & a whole new district.

I have many great stories & memories about discoveries & prospectors I met. Hopefully, I will be able to find time to write a book about these, as such stories should be preserved. There are stories about hundreds of nuggets in ball jars in Shorty Haddenham’s trailer at Atlantic City, dozens of nuggets found by a Ft. Collins prospector, a prospector who spent one entire winter jumping a claim & panning out barrels of mica thinking he had found the Mother Lode & my research along the UP corridor- we found gold everywhere including the Laramie City dump.

Gold photos below – 34 oz nugget (Rock Creek, South Pass), gold from Douglas Creek, and gold from Dickie Springs (South Pass).

I mapped the South Pass greenstone belt at the southern tip of the Wind River Mountains which included several historic gold districts: Lewiston, South Pass, Atlantic City, Miners Delight & others. I identified several hundred gold anomalies & found gold was structurally controlled in reef ore shoots that are very rich down plunge. One deposit I mapped (Carissa) is a major deposit 1000 ft wide, 1200 ft long & probably continuous a few thousand feet downdip. This deposit was withdrawn by the legislature without any scientific review – such abuse of political power literally took away a mountain of gold & many good jobs.

Geology led me to many discoveries. The Rattlesnake Hills were an obvious target, so in 1981, armed with the concept that the RH were part of a fractured greenstone belt intruded by Tertiary alkalic volcanic rocks, I knew there had to be gold. And I found gold in the RH in veins, shears, Tertiary breccias, stockworks, pyrite. I also found significant gold elsewhere in Wyoming – Seminoe Mountains, Mineral Hill, Purgatory Gulch, more.

Left – Gold at the end of the rainbow at the Duncan mine, & view of part of the auriferous shear at the Carissa – a major gold deposit with potentially >US$billion in gold.

HEY, there are several other (Older Posts) – be sure to check them out by clicking on Older Posts below


During 30 years at the WGS, I found hundreds of deposits. How did I do this? I used geology as a guide; I looked at things differently and was motivated to look and search for mineral deposits.

While conducting reconnaissance, I discovered jasper in several old mines at Tin Cup, in an outcrop near the south edge of the Rattlesnake Hills, and found jasperoid at Quaking Asp Mountain. Some of the Tin Cup jasper is extraordinary and found in masses weighing several hundred pounds. The jasper in the Rattlesnake Hills contained some fossil leaf imprints.

Nearly everywhere I explored, I followed trends and examined geology which lead me to other mineral deposits. I was curious enough to find out what some of the unusual minerals were that I picked up, and as a result, I identified more than a dozen minerals that had never been reported in Wyoming.
Above – barite from Mine Hills, Shirley Basin. Middle- a group of cabochons cut from various material. Below – beautiful jasper from Tin Cup & me standing in old prospect pit. These prospects were reported as having high-grade gold values. I found no gold & likely these were left over from various gold mining frauds and scams from the 1800s. Note the large mass of jasper to my right (probably a few tons of high quality material).

Left – Labradorite feldspar collected by Norma Beers in the road bed of Albany County 12 in Albany County. This is just one of millions of gem-quality feldspar found in this area – yet this resource remains unexplored.


A rockhound from Riverton mentioned opal south of town. The Cedar Ridge deposit lies along the highway & is cut by numerous oil field roads, no one had recognized that this place had one of the largest opal deposits on earth! A few old geological reports from 50 years ago briefly mentioned opal, so I was surprised to find opal scattered over 14 mi2, opal masses >79,000 cts along the edge of the road & common, fire & precious opal with scattered Sweetwater agate & some of the nicest decorative stone on earth. All within Tertiary age volcaniclastic sedimentary rocks that had a notable contribution of volcanic ash erupted from Yellowstone in the geological past.

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!
Photos show precious opal, Sweetwater agate, cobbles of opal in oil field adjacent to road. Below are fire and common opal


A 16-carat iolite from Palmer Canyon, Wyoming.

I discovered iolite (water sapphire) at Palmer Canyon in 1995. The iolite occurred with gem-quality kyanite in mica schist & gneiss adjacent to vermiculite that had enough silica to form these gems. I couldn’t believe the amount, size & beauty of the stones. The single, largest, iolite gemstone on earth was found at this time -the baseball sized Palmer Canyon Blue Star- a 1,720 ct flawless gem.

First group of iolites gems cut from
Palmer Canyon rough. The bed of
material that the iolites sit in has tiny
white fibers that unfortunately sit
in front of the iolites at the top. But
these iolites were flawless.

So I went looking in similar terrains & predicted in a book I would find iolite at Grizzly Creek to the south. In 2005, I discovered iolite at Grizzly Creek & recovered the largest iolite gem (24,150 carats) on earth (the football sized Grizzly Creek Blue Giant), but this was dwarfed by giant, VW bug-sized masses in the outcrop I left behind because I didn’t have tools necessary to recover such large gems of 1 to 5 million + carats. Based on geology, I predicted several other iolite deposits would be found in central Laramie Range & Copper Mountain, but most remain unexplored. Over the years I tried to get some investors interested in forming a company to take advantage of these giant deposits – explore for more, mine them, cut the gems, design jewelry and market them, but no one wanted to take on this task, so they all essentially sit there collecting dust and eroding away.

But nothing could match the potential discovery further to the south. Some geologists had explored this region for aluminum & magnesium & during the mid 20th century and they reported one deposit that had been trenched and mapped contained 500,000 tons of cordierite (when gem-quality, cordierite is known as iolite). I began looking at this deposit & found flawless gem-quality ioilte along the edge of the deposit. All of the material reported by theses earlier geologists likely was part of the largest gemstone deposit found in history. But they were so focused on the use of the material for magnesium and aluminum, they overlooked the gem potential. Besides, in the mid-20th century, there was not much of a market for iolite gemstones.

Iolite in outcrop at Grizzly Creek, Wyoming. Note the rusty matrix to the
right of the iolite. This is limonite replacing the iolite. Iolite has considerable
iron and will ‘rust’ under the right conditions.

But let’s look at this deposit as a potential gem deposit. It is unexplored for gems except along the one margin where everything I examined was of the highest quality gem material. The rest of this deposit needs to be examined. Why?  One ton of material contains 4.5 million carats! Multiply that by 500,000 tons and this could potentially have more than 2 trillion carats just on the surface and no one knows how deep it goes. If it is just 100 feet deep (it likely is a few thousand or more feet deep), it would dramatically increase the amount of recoverable gemstones. Iolite sells for only about $15 to $150 per carat, but if marketed like Tanzanite was marketed, one could increase the value of this (and other deposits in this region) to the most valuable mineral deposits on earth! But to develop this will take a lot of money and support.

The Palmer Canyon blue Giant sits on cover of
ICMJ Prospecting & Mining Journal. At 1,750
carats, this was the largest iolite gem reported
in the literature until I found much larger
stones at Grizzly Creek, Wyoming.

So what did I get for finding two of the largest colored gemstone deposits on earth? Well, like the song goes, the director got the mine and I got the shaft. But am I bitter? Yes!

Largest iolite in world at 24,150 carats from Grizzly Creek, Wyoming. Much larger stones were left in outcrop.


Ruby & Sapphire are beautiful stones. In 1995, I discovered my first ruby-sapphire-corundum deposit mixed with iolite & kyanite at Palmer Canyon west of Wheatland. After I recognized this association of gems with a rock type known as vermiculite, I started searching other vermiculites. It turns out that vermiculite is a alteration product known as glimmerite formed by retaining aluminum in the original rock & removing all silica (under pressure). Thus, one ends up with a rock that is essentially nothing but aluminum-rich mica. Ruby and sapphire are aluminum oxides are require high pressures and temperatures to form (as well as a good source of silicate poor aluminum). (photos above show one of the largest rubies found on earth at the Red Dwarf deposit. Sample is partially replaced by green zoisite; and a pink sapphire with excellent cleavage from vermiculite. Middle photo is a 1.1 carat ruby cut from material at Palmer Canyon and lower photo is a ruby from the Red Dwarf).

Earlier work in the Elmers Rock greenstone belt had shown rocks in the central Laramie Mountains formed at great pressures & temperatures that were high enough one might expect to find ruby & sapphire. So I was not surprised when I found these gems. Luckily, two geologists had put together a report on vermiculite in the 1940s, so I took their publication & began searching all vermiculite deposits for ruby – about 30% contained ruby! In addition to these, other rubies were found in the southern Wind River Mountains & the source remains to be found, even though some rubies found by prospectors weighted as much as 80 carats. At another deposit in the Granite Mountains, I mapped 3000 ft of ruby schist at what is known as the Red Dwarf deposit & recovered some of the largest rubies ever found.


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.


A good understanding of geology, persistence & some 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, the most recent published by Booksurge at Amazon.

MORE information at GEMHUNTER.

Some of the many gemstones discovered in Wyoming since 1977.

Major Diamond and Colored Gemstone Deposits Found in US


See also

State Line Kimberlite Province showing locations of (1) Radichal kimberlite &
Mineral Indicator Anomalies, (2) the Iron Mountain kimberlite district, (3) Schaffer,
Aultman, Ferris kimberlites, (4) Keslsey Lake Kimberlites (5) Nix kimberlites, (6)
Sloan kimberlites, (7) Estes park kimberlites, (8) Boulder Kimberlite, (9) Boden
diamond placer. In between these are several hundred cryptovolcanic structures
with similarities to kimberlite pipes as well as more than 300 kimberlitic mineral

False-color aerial photo shows a few of the several hundred
cryptovolcanic structures that have been found in Colorado
and Wyoming. These structures are lake filled, structurally
controlled depressions with carbonate-rich soils
on shore lines. Are these just lakes? Or
are they diamondiferous kimberlites? Note the roads near
these structures to get an idea of scale.

Research suggests that the Wyoming Craton encloses a world-class diamond province as well as major deposits of colored gemstones. The Wyoming Craton includes portions of Colorado, Nebraska, Kansas, Montana , Wyoming, Alberta & Saskatchewan, & encloses the two largest known kimberlite districts in the US & the largest lamproite & lamprophyre fields in North America. Diamonds have been reported in kimberlites and lamprophyres in this craton in Canada, Montana, Wyoming, Colorado and Kansas.

Winkler Crater in Kansas with two trenches dug to sample the material.
Originally classified as an impact crater until it was verified by Doug
Brookins to be kimberlite. Tested by Cominco American in the 1980s
the pipe may have yielded one microdiamond, but there is concern that
the diamond may have been contaminate from the State Line district.

Hundreds of kimberlites, lamproites and lamprophyres were identified over the past few decades. In addition the many known diamondiferous kimberlites & lamprophyres, in recent years, four significant iolite (water sapphire) deposits were found as well as deposits of ruby, sapphire, opal, kyanite gems, jade, chromian diopside (Cape Emerald), pyrope garnet (Cape Ruby), almandine garnet, spessartine garnet, peridot, gem-quality apatite, jasper, agate, onyx and other gems – all found since about 1975. Two of the iolite deposits are world class. This region has turned into an exploration geologists’ and rockhounds’ paradise.

Consulting geologist W. Dan Hausel identified hundreds of cryptovolcanic structures within this province over the past several years. Many are quite large and some are situated within known diamond districts and in large areas that remain unexplored. In addition to the the known kimberlite, lamproite and lamprophyre districts, more than a dozen new districts containing many cryptovolcanic structures were discovered. As incredible as it seems, a few lie adjacent to interstates and highways and have been missed by millions of travelers every year.

Cryptovolcanic structure (kimberlite) in Colorado showing open park associated with depression.

During the past 30 years, the two largest diamondiferous kimberlite districts in the US and the largest field of lamproites in North America were mapped in the Colorado-Wyoming region. Several hundred kimberlitic indicator mineral anomalies were also scattered all over Wyoming, parts of Colorado, Utah, Montana, Kansas and Alberta. Other researchers found similar anomalies.

The several hundred cryptovolcanic structures have characteristics that suggest most are kimberlite pipes. They are circular to elliptical in shape, structurally controlled, many are distinct depressions with distinct vegetation anomalies similar to kimberlites mapped in the past. Some of the depressions are so distinct that they have actually been mistaken as impact sites, such as the Winkler crater in Kansas, that was originally thought to be an impact site, and later discovered to be kimberlite, and a few depressions that were identified in the central Laramie Range and Medicine Bow Mountains. Field examination of many depressions show visible blue ground and carbonate-rich soil, with rounded boulders and cobbles –characteristics that are generally associated with kimberlite. In addition, samples from some sites yield the traditional kimberlitic indicator minerals.

Historically kimberlite pipes were described in 19th century South Africa as having ‘blue ground’, considerable calcium carbonate, and were thought to be old dry stream placers because they contained rounded cobbles and boulders (similar to the cryptovolcanic structures found in the Wyoming craton). The rounded boulders were instead due to country rock fragments that had been rounded and polished in the kimberlite magma as it erupted a few hundred million years ago.

Diamonds from Arkansas – photo
from Glenn Worthington

A few of these structures may represent some of the larger pipes in the world. The best explanation for most of these depressions is that they represent soft, circular deposits of rock that is dramatically different from the more resistant and harder basement granite and gneiss country rock they intrude. Kimberlite typically erupts in circular maar-like volcanoes and is a relatively soft rock. This is why so many kimberlites discovered in Canada as well as in the Wyoming craton form distinct open, treeless parks, with several being submerged under shallow ponds and lakes.

Such structures have been found in the Laramie, Medicine Bow, Front and Seminoe Mountains, the Green River Basin, Bighorn Basin, eastern Kansas, and Alberta. Several hundred were found as far south as Denver Colorado, to as far north as central Alberta, and as far west as Little America to as far east as eastern Kansas. In the vicinity of the Colorado-Wyoming border, Hausel mapped the State Line district with more than 40 diamondiferous kimberlites. Some of these form distinct circular depressions and have already be verified as diamond pipes.

Rough diamond with trigons

Unfortunately, only a few of the anomalies and the known kimberlites, lamproites and lamprophyres have been tested for diamond. But nearly all that have been tested yielded some diamonds. The State Line district alone produced more than 130,000 diamonds during testing in past years. No one really knows what awaits discovery here as past diamond testing was inefficient.

For example, the four diamond mills constructed to test various diamond deposits in the State Line district had many significant flaws & evidence supports that they only recovered a small portion of the diamonds. Even so, gem diamonds >28 carats were recovered along with a octahedral diamond fragment from a larger diamond estimated at 80 to 90 carats. But much larger diamonds were very likely missed by the mills, and these deposits likely contain hundreds of thousands of carats! In Wyoming, kimberlites yielded 50% high-quality gem diamonds. In Colorado, about 30% with gem-quality.

Little effort to outline this resource has been done by the respective state geological surveys in recent years. Research expenditures on diamonds in Wyoming, Colorado, Montana & Kansas has been nearly non-existent compared to the tens of millions of dollars spent for Canadian research along with the hundreds of millions in exploration by companies. Canada now has some commercial diamond mines developed since 1998 an others in the planning stages. In fact, state and federal agencies in the US, which should be conducting research, have only hindered research.

Past work has shown that nearly 50% of the diamonds in this craton have been very high quality gemstones. But at the pace that various government agencies are investing to outline this resource (currently non-existent) is shameful and little will happen until a major diamond is accidentally found by a prospector or rock hound.

Diamonds from the State Line of Colorado & Wyoming

In Canada, it typically takes $1.5 million per discovery (whether diamondiferous or barren). The Wyoming Geological Survey invested about $20K in research over the past 30 years! – “It is no wonder why nothing is happening, yet a new multi-$billion dollar industry potentially awaits discovery”.
And the author believes he has found enough kimberlites, anomalies and colored gemstone deposits in this region that could have enough value to pay for a significant portion of the national debt (prior to Obama). In addition to significant diamond resources, two world-class colored gemstone deposits were discovered along with other major and significant gem deposits. The area not only provides some of the better samples of kimberlite, but has also been the most productive in the US as far as the number of diamonds recovered.
Hundreds of kimberlite pipes occur in a large group of 12 districts within a major diamond province in Colorado and Wyoming. Some of the recently discovered districts enclosed as many as 50 known cryptovolcanic structures (along with potentially dozens of hidden kimberlites).

Aerial photos showing (left) – one of more than a dozen distinct cryptovolcanic structures (depression filled with rounded boulders & cobbles containing calcium-carbonate-rich soils within a granitic terrain) in the Happy Jack area west of Cheyenne.

And (right) aerial photo of one of the largest cryptovolcanic structures in North America at the Twin Lakes field south of Interstate 80 west of Cheyenne. This field of >50 such structures (kimberlites?) are outline by distinct vegetation anomalies, depressions in silicate-rich Proterozoic age granites & gneisses in cratonized belts, have considerable calcium-carbonate salts (white bull’s eyes), rounded boulders, are structurally controlled and located between the State Line and Iron Mountain diamondiferous kimberlite districts.

The author discovered these in the State Line district, the Red Feather Lakes district, the Boulder district, the Happy Jack district, Horse Creek district, Iron Mountain district, Middle Sybille Creek district, Indian Guide district, Harrison district, Twin Mountain district, Eagle Rock district, King Rock district, Strong Creek district, Grant Creek anomaly, Lone Pine field, Lost Lake field, Creedmore Lake field, Chicken Park field, BG field, Lake Owen district, and the Douglas Creek district. Very few of these are tested but provide evidence for one of the largest kimberlite provinces in the world. IN the past, the author mapped the two largest diamondiferous kimberlite districts in the US (Iron Mountain and State Line) in this region.

One of the largest lamproite fields in the world (Leucite Hills) and one of the largest lamprophyre fields in North America (Missouri Breaks) occurs in this region, and few of these have been tested even though a group of lamprophyres near Cedar Mountain Wyoming contain diamonds and several lamprophyres have produced diamond-stability minerals, and evidence suggests that one of the largest lamprophyre fields in the world is located in southwestern Wyoming near the Leucite Hills lamproite field.

Placer diamonds are likely to be found all over the region, but little exploration has occurred. In the state line district, the kimberlites are deeply eroded providing geological evidence for a very large placer diamond population to occur in the adjacent draininges. To date, only a few samples have been taken in these drainages, yet placer diamonds as large as 6.2 carats were recovered in the past.


One deposit discovered more than 10 years ago yielded the largest iolite gemstone in the world at the time of the discovery – a >1700 carat iolite. Recently, a world-class iolite deposit was discovered where a >24,000 carat iolite gemstone was collected, but masses of gem were identified in outcrop that are estimated to weigh >a million carats. At another deposit, high-quality iolites were verified, where past exploration accidentally identified a deposit that could be the largest ever found – it is suggested that this latter deposit could host more than a trillion carats of iolite (iolite sells for $15 to $150/carat).

Many other gemstone deposits are suspected in this region. For example, nearly a dozen ruby deposits were found by searching favorable geological regions and recovering rubies in stream sediment samples while searching for diamond deposits. Need more information on diamonds, other gemstones and how to find them? We are putting together a newsletter to send out to interested prospectors and geologists – write to us at:
Photo of outcrop of iolite in central Laramie Mountains.

And, I’ve always wanted to see if I could cleave a large diamond with my hand. So, do you have a giant diamond you would like to donate to this research project? Diamond verses Karate.

Diamond Books by the author