Thursday, October 3, 2013

Iolite Gemstones Discovered in the Rocky Mountains

Beautiful water sapphire, also known as iolite, found in the central Laramie Mountains by the Gem Hunter.
Cordierite had been known to occur in metamorphic rocks in the cores of some of Wyoming mountain ranges for decades. But it wasn’t until 1996, that the gem variety of the mineral, often referred to as iolite, was discovered in Wyoming. When gem-quality; cordierite is known as ‘iolite’ or ‘water sapphire’ and sometimes referred to as 'dichroite'. The initial discovery of iolite in Wyoming was made when the author began searching for ruby in a rock known as vermiculite schist that is sometimes referred to as glimmerite by some foreign geologists.

The Palmer Canyon Blue Star - 1,720 carat flawless gemstone. This was the largest iolite ever found in 1996. However, a
 few years later, the GemHunter (a.k.a. Dan Hausel) recovered the Grizzly Creek Blue Giant - of more than 24,000 carats,
and left specimens in outcrop estimated to weigh several hundred thousand carats and more. Some gemstones in the
 outcrop were similar in size to a VW bug and likely weighing in the millions of carats!
Gemologists and mineralogists have no problem distinguishing iolite from similar minerals, but the highest quality of iolite is difficult for the lay-person to distinguish from oriental (blue) sapphire and tanzanite, as all three stones yield beautiful gems. However, if you search a local jewelry store for these three, most will not have iolite, because of its rarity, even though the gemstone is considerably lower in value.

Beginning with the discovery of iolite at Palmer Canyon in 1996 (Hausel, 1998b) followed by discovery of giant gemstones in the Grizzly Creek area in 2004 and iolite in the Ragged Top-Sherman Mountain area and at Owen Creek in 2005 (Hausel, 2004, 2005) in the central Laramie Mountains, it became clear, that Wyoming was no longer just a 3rd rate gem state. It was the premier gemstone state in the US! No other state could boast of having such a great variety of gemstones - many were discovered by the author over 3 decades and added to the already spectacular jade deposits and to the diamond deposits in the state. But soon polytickans stuck their nose into these research projects and by 2006 the research ended - even though there are likely hundreds of more gemstone deposits in Wyoming. By the time I left the Wyoming Geological Survey in 2006, I had evidence for more diamond, gold, iolite, ruby, sapphire, opal and even emerald deposits in Wyoming. What is a poly-tick-an you ask? It use to be spelled politician, but Jay Leno set us straight when he indicated it really meant 'poly' = 'many' and 'tick' = 'little blood sucker'. But to be honest, I did meet some very good republicans in Wyoming.

The discovery of gem-quality cordierite in Wyoming was thought to be one of the great gemstone discoveries in the United States in many decades. Even though four separate iolite deposits were discovered, beginning with the 1996 discovery, little effort has been made by the State of Wyoming to research, mine, facet and market these attractive gemstones since 2006. With good marketing strategy, it should be possible to produce a tanzanite-like frenzy of this rare gemstone primarily mined in Sri Lanka in placer deposits. Because of the lack of mining of iolite gems worldwide, iolite is difficult to find in jewelry stores in North America. Go ahead, visit a local jeweler and ask if they have any iolite jewelry. The answer is often - "no, but we wish we had some because we get many requests". Wyoming appears to have the largest iolite resources in the world and Wyoming’s geology is favorable for discovery of other gemstones including some weighing several hundred thousand carats!
Fractured but transparent iolite from Palmer Canyon. This
stone could easily produce several high-quality gemstones.

Cordierite is an alumino-silicate found in a region with other alumino-silicates such as andalusite, kyanite and sillimanite. These porphyroblasts occur in alumina-rich mica schists known as metapelites. In Wyoming, cordierite has been reported in several areas including Copper Mountain in the Owl Creek Mountains (Hausel and others, 1985), South Pass in the Wind River Mountains (Hausel, 1991a), the Seminoe Mountains (Hausel, 1994b), the Laramie anorthosite complex, and the Elmers Rock greenstone belt in the central Laramie Mountains of southeastern Wyoming (Graff and others, 1982). Only four deposits to date have yielded gemstones, but little exploration has occurred for this gemstone.

Cordierite (Mg,Fe3+)2Al4Si5O18, is an orthorhombic mineral that typically forms short prismatic pseudo-hexagonal crystals with rectangular cross sections, as well as massive, compact minerals of various shades of blue, bluish-violet, grey, or brown. According to Sinkankas (1964), repeated twinning on a crystal surface (mineralogists refer to this surface as m{110}) results in cordierite having near hexagonal (6-sided) cross sections when a crystal shape can be recognized. However, some cordierite will have district crystal shapes and others are found as granular to massive specimens. Cordierite has poorly developed cleavage, but parting parallel to crystallographic c-axis [m{001}] may occur in altered crystals.

Much cordierite in Wyoming is poor-quality, opaque to translucent, white-grey to brown porphyroblasts found in mica schist. When found as a gemstone, the mineral will be translucent to transparent cordierite known to gemologists as iolite or dichroite. The first documented and verified discovery of iolite in Wyoming occurred in 1996 in the Palmer Canyon area of the Laramie Mountains west of Wheatland in eastern Wyoming. The mineral occurred near outcrops of vermiculite schist that were filled with sapphire, some ruby, and considerable kyanite.

The iolite has oily to vitreous luster, is sapphire-blue in color with marked pleochroism that changes from sapphire-blue to violet-blue depending on the direction the mineral is viewed in light.  Pleochroism is the result of absorption of different wavelengths of light along different crystallographic  directions. Minerals (uniaxial minerals) such as iolite that have pronounced dichroism that produces two pleochroic colors and are said to be dichroic. For those of us who are not mineralogists, this simply means that the color of the mineral will appear to change as the transparent to translucent crystal is rotated in light.

Cordierite is often found in pelitic schists in Wyoming. Pelitic schists are simply schists that have abundant aluminum-rich minerals such as biotite and muscovite. It has also been found as mineral replacements of other alumino-silicate minerals such as andalusite, sillimanite and/or kyanite (under the right conditions, certain minerals will replace others over time). When unaltered, cordierite will have a hardness of 7 and low specific gravity of 2.55 to 2.75. The specific gravity of cordierite increases with increasing iron content. Sinkankas (1964) reported the specific gravity for transparent gem-quality cordierite to lie within the range of 2.57-2.61.

So after making several dozen gemstone discoveries, millions in gold, mapping more than 400 square miles of geology in mining districts along with the two largest kimberlite districts in the US and the largest lamproite field in North America, and publishing ten times as many professional papers, books and maps than the rest of the geological staff combined, and assisting hundreds of members of the general public, both Ray Harris's (RIP) field vehicle and my field vehicle was confiscated. Sad to say that one of the four top State Geological Surveys in the country was taken to the bottom in a short years by a couple of polytickans. 

Iolite in outcrop. You can see the gem-quality blue stone and the yellow or tawny-colored oxidation coating on more iolite.
Also note that iolite continues in every direction from the center of the photo to several feet off of the photo. This one
 outcrop here has several hundred thousand carats of gemstones and likely more than a million carats!
This 100+ carat gemstone was one of hundreds found at Palmer Canyon in the central Laramie Mountains by the Gem Hunter.
Some of the many gemstones discovered by the Gem Hunter -
these are Ruby, brown sapphire and water sapphire. The ruby
weighed 1.1 carats.
Photo taken of the Gem Hunter (me) after I made a discovery of gem-quality
iolite, ruby, sapphire and kyanite in the Palmer Canyon area of the central
Laramie Mountains. My foot is on kyanite schist.

Tuesday, October 19, 2010

A NEW SOURCE OF WYOMING GEMSTONES (Iolite, Ruby, Sapphire, Kyanite)

Group of faceted ruby, pink sapphire &
iolite, Laramie Range, WY
In 1995, field reconnaissance in the central Laramie Range of southeastern Wyoming led to the discovery of a new source of gem- and near-gem-quality cordierite and corundum hosted by quartzofeldspathic gneiss and gem corundum and gem kyanite chlorite-biotite schist and mica-kyanite gneiss (Hausel, 2002). Prior to this discovery, iolite was essentially unknown in Wyoming other than one obscure reference made by John Sinkankas about an extensive iolite gemstone deposit with no location given. This discovery led to additional iolite gem discoveries at Grizzly Creek in 2004 and Sherman Mountains in 2005 as well as gem ruby and sapphire deposits elsewhere in Wyoming.

Previously, cordierite had been reported at Owen Creek by Snyder and others, 1995 with no mention of gemstones. During investigations of this occurrence, the author identified gem iolite and sapphire in 1996. The geology and metamorphic grade of the central Laramie Range is suitable for a number of alumina-gemstones including iolite, kyanite, ruby, sapphire, andalusite and sillimanite. Exploration of anorthosites, syenites, metapelites and vermiculites in this region will likely lead to many additional discoveries.

The first iolites (0.36 to 1.33 carats) & sapphires
(1.15 to 1.47 carats) faceted from Palmer Canyon
cordierite & corundum recovered by the author.
Photo by Maha Tannous (courtesy of GIA).
These gneisses and schists occur near the margin of the Elmers Rock greenstone belt, an Archean synformal belt of amphibolite-grade metasedimentary and metavolcanic rock within the Wyoming Province (Graff and others, 1982). The Wyoming Province represents an Archean (>2.5 Ga) basement complex, which underlies much of Wyoming and a large portion of Montana (Hausel, Edwards, and Graff 1991).

Several other gem and semiprecious mineral occurrences have also been identified in Wyoming (Hausel and Sutherland 2000). These include aquamarine, chrome diopside, diamond, jade, labradorite, olivine (peridot), opal, pyrope garnet, variscite, and many unique agates and jaspers. Based on favorable geology, further field investigations will undoubtedly lead to additional gemstone discoveries as well as more iolite discoveries. The geology, geochemistry and metamorphic grade in the central Laramie Range are very favorable for crystallization of iolite, ruby, kyanite and possibly gem sillimanite and andalusite.


The cordierite and corundum occurrence is within Palmer Canyon along the eastern flank of the central Laramie Range of southeastern Wyoming. Palmer Canyon lies about 16 miles west of Wheatland, a farming community with a population of about 3,500. This community is located along the northern edge of the Denver Basin nearly 70 miles north of Cheyenne. At an elevation of 4,730 feet above sea level, Wheatland has a comparatively mild climate. Recorded temperatures range from a low of 0°F to a high of 105°F. The Palmer Canyon occurrence is located at 5,760 feet above sea level, and nearby peaks reach heights of 6,000 to 7,700 feet, with the highest peak in the Laramie Range (Laramie Peak) located 10 miles to the north at an elevation of 10,019 feet.

Location map of Palmer Canyon
The mineral occurrence is accessible by driving west from Wheatland on the Palmer Canyon road, which is paved from Wheatland to within 0.8 mile of the deposit. The ownership of the deposit is split, such that the surface is private and the minerals are reserved to the Federal government (Vic Norris, personal com, 2001). Claims were filed for gemstones on the mineral estate a few years after I made the discovery. Thus permission may be necessary from the claimant.

Nearby Occurrences
In addition to Palmer Canyon, several other interesting occurrences are found in this region (Hausel and Jacobson 2001). The largest group of diamondiferous kimberlites in the United States, which form the State Line district, are located 80 miles to the south (Hausel 1998). Approximately 130,000 gem- and industrial-quality diamonds have been recovered from this district. Thirty miles south is the second largest kimberlite district in the United States, known as the Iron Mountain district (Hausel et al 2000), which remains relatively unexplored for gemstones, even though the kimberlites appear to be favorable hosts for diamond (Hausel et al, 2002). Twenty miles south, some labradorite feldspar with excellent fire is found within the Laramie Range anorthositic batholith (1.5 Ga). I have been told that one can even find this gemstone in the road bed material along Albany County 11 and 12 (Norma Beers, personal communication).

Blue, transparent, barite from the Casper Formation (Pennsylvanian) located 30 miles to the west in the Shirley Basin, provides a source for attractive mineral specimens. Attractive agates and agatized breccias located within the Hartville uplift 30-40 miles to the northeast, provide a lapidary source to collectors in the region (Hausel and Sutherland 2000). In addition, the author discovered several hundred cryptovolcanic structures in this region, many have characteristics similar to kimberlite pipes.

The region surrounding the Palmer Canyon deposit is relatively unexplored. Nearby pelitic schist and vermiculite with similar geology to the Palmer Canyon occurrence, remain unexplored.


Palmer Canyon is located within the Wyoming craton in an area mapped as undifferentiated Archean granite-gneiss (Graff et al 1982). This craton was established by 2.7 Ga (Eggler and others, 1988).

 Quartzofeldspathic gneiss, granite gneiss, pelitic schist, and biotite-chlorite-vermiculite schist all occur within the Palmer Canyon deposit. Although there is no evidence that this deposit had ever been investigated for gemstones in the past, a small segment of the schist was briefly investigated for vermiculite prior to 1944. According to Hagner (1944), this occurrence, known as the Rolf prospect, was found in a N80°W trending, 65°SW dipping, biotite schist, which locally contained chlorite, kyanite, and corundum. The deposit was interpreted to have formed by the replacement of biotite by vermiculite under the influence of pegmatitic fluids (Hagner 1944). Cordierite was not mentioned, and no physical descriptions of the corundum were provided by Hagner.

  During field investigation in 1995, only one small prospect pit, about 3 feet deep and 3-4 feet across was found. Even though some samples of vermiculite-chlorite-biotite-corundum schist were found in the pit with as much as 20 percent corundum, there appears to have been no investigation into the potential for gemstones. Vermiculite was sought in the 1930s and 1940s as fire-resistant insulation. Following this investigation, the author discovered about 30% of vermiculite deposits in Wyoming contain ruby and sapphire showing a positive connection of these gemstones with the alumina rich rock.

Gneiss outcrop at Palmer Canyon
Vermiculite was never commercially mined from the deposit.

Thus, as a gem-prospector, you should get to know this rock type thoroughly (take some samples if you visit this spot), as there is good evidence that vermiculite is a highly aluminous altered rock that provides favorable conditions for a number of aluminum rich gemstones including ruby and sapphire. After you learn about this rock type, search Wyoming, Colorado, and Montana for vermiculites. Several vermiculites in the world are sources for ruby and sapphire!

Based on field reconnaissance, XRD (x-ray) analysis, and microscopic studies the Palmer Canyon deposit hosts five types of gemstones and near-gems. These include: (1) violet to blue, transparent cordierite (iolite), (2) dark-gray transparent cordierite, (3) reddish transparent to translucent corundum (dark pink sapphire), (4) white to light pink translucent corundum (sapphire), and (5) white to pink translucent to opaque corundum. In addition, low quality, dark gray, translucent to cloudy cordierite is also present, as is some corundum with well-developed rhombohedral parting that tends to crumble. These have little value as gems.

Cordierite (Mg, Fe)2Al4Si5O18, crystallizes in the orthorhombic (pseudohexagonal) crystal system. It typically forms short prismatic crystals with rectangular cross-sections but often exhibits elliptical to rounded morphology due to alteration or resorption caused by disequilibrium conditions at depth. The mineral is brittle, has conchoidal fracture, and may have poor cleavage parallel to b{010} and parting parallel to c{001}. It ranges in hardness from 7 to 7.5 and has a specific gravity of 2.55 to 2.75.

 According to Sinkankas (1964), the gemological term for cordierite is iolite. The word iolite is derived from the Greek word ion, meaning violet, is the common color of gem-quality cordierite. The color of cordierite may vary from yellow to green to blue to violet, but only the transparent blue and violet-blue grains are prized for faceting.

 Cordierite is often referred to as dichroite due to its strong pleochroism, which produces gemstones that appear to change shades of color depending on the angle it is viewed. In one direction, the iolite will appear sapphire-blue; when rotated, it will appear to be light grayish-blue to gray.

 Corundum, Al2O3, typically occurs as tablet- or barrel-shaped, hexagonal prisms with basal terminations. The basal terminations often have distinct regular, triangular, striations, which are an expression of rhombohedral parting. The basal terminations themselves, are expressions of basal parting.

Gem ruby from Palmer Canyon, Wyoming (about 12 carats).
 Corundum with a hardness of 9, is second only to diamond in hardness. It has relatively high specific gravity (3.94 to 4.08) which results in detrital corundum sometimes being found concentrated in placer deposits with other minerals of high specific gravity such as gold, magnetite and garnet.

 Most natural corundum is of industrial quality, but transparent to translucent varieties with their adamantine to vitreous luster, potentially yield gemstones known as ruby and sapphire. Red gem-quality corundum is known as ruby; all other colors of gem corundum are referred to as sapphire with a prefix denoting the color of the stone (Hurlbut and Switzer 1979).

 The most desirable color of ruby is dark, purplish-red, known as pigeon's blood ruby. The most desirable color for sapphire is velvety cornflower blue called Kashmir blue. Some rubies and sapphires may exhibit asterism. Such stones exhibit six-rayed stars of light produced from light reflecting off oriented, needle-like, mineral inclusions of rutile within the corundum (Hurlbut and Switzer 1979). The needle-like crystals lie in planes perpendicular to the c-axis of the corundum.

Vermiculite schist filled with pink sapphires and blue kyanite
from Palmer Canyon, Wyoming
 Corundum may occur as an accessory mineral in some metamorphic rocks such as mica schist, gneiss, and crystalline limestone. It may also occur as a secondary mineral associated with contact metamorphism of limestone. It has also been found in silica-poor igneous rocks such as syenite, nepheline syenite, serpentinite, and lamprophyre (Hurlbut 1966; Bauer 1968; Hausel 1996). In Wyoming, corundum has been found in gneiss, pelitic schist, and vermiculite schist.

Wyoming Occurrences

Cordierite Other than the Palmer Canyon occurrence, no other sources of gem-quality material are known in the state. However, Sinkankas (1964) mentions a massive cordierite deposit with gems capable of being cut found in Wyoming. Unfortunately, no location and no other information were given, and no records of this occurrence exist. Communication with John Sinkankas in 1995 indicated that he could not remember where this deposit was.

Mineralized terrains and mining districts of Wyoming (after Hausel).
Cordierite has been described in the South Pass greenstone belt of the Wind River Mountains in western Wyoming (Hausel 1991), and has also been identified in the Copper Mountain supracrustal belt of the Owl Creek Mountains in northwestern Wyoming (Hausel, Graff, and Albert 1985). Cordierite in these two metamorphic belts forms opaque, black to brown, rounded porphyroblasts typically less than 0.5 inch across. Many of the grains are partially to entirely replaced by fine-grained sericite and quartz.

Cordierite was also described to occur as almond-shaped masses in schist within the Sierra Madre southwest of Encampment, in southeastern Wyoming. The mineral is also described in baked shales and clays above burned coal beds in the Powder River Basin in northeastern Wyoming (Osterwald and others, 1966).

The largest occurrence of cordierite in the state (as well as the world) may possibly occur in the Laramie anorthosite-syenite complex in the central Laramie Range south of Palmer Canyon and Grizzly Creek according to early reports on cordierite. Osterwald and others (1966) described widespread, lenticular to tabular layers of cordierite in metanorite, syenite, and syenite-diorite gneiss along the northern margin of the complex. Some of the metanorite was reported to contain as much as 50-80% cordierite. The early reports indicated that this deposit (based on trenching and surface sampling) contained approximately 500,000 tons of cordierite!!! What does this mean?

One carat weighs only 0.2 grams and one ton has 4,536,000 carats! Thus if we were to assume this deposit was nothing but gem material, this would equal 2,268,000,000,000 carats (2.268 trillion carats)!

Of course, we do not know how much of this deposit is gem quality, but even if it is a small percentage, this could be the largest colored gemstone deposit on earth if the early (pre-world war II) geological resource estimates are correct. But also realize that this resource was based only on surface samples and not on drilling, thus this cordierite resource could be many times this size if we were to drill it to a depth of say just 100 feet.

Unfortunately, I was unable to do much investigation of this deposit other than to collect a few samples along the road between Laramie and Iron Mountain. Here, all samples of cordierite were in the range of 1 to 4 carats and all were flawless gemstones.

Group of 8 to 12 carat iolites faceted from Palmer Canyon cordierites
Samples from the Vic Norris collection.
At the time of this discovery the State of Wyoming was controlled by the democratic party (governor and state geologist) and all of a sudden several members of the Wyoming Geological Survey were in trouble with management - field vehicles were confiscated and given to the WGS secretary, selected members of the staff were not allowed to present any more talks to professional groups or prospectors, and publications were restricted, etc. It became a nightmare for about half of the 2004-2006 staff. Two staff members suddenly died - a third died a few years later, and five were being treated for sudden heart conditions. Coincidence? No investigation ever occurred.

But back to the minerals in Wyoming. Elsewhere in the Laramie Range, cordierite has been reported in the Grizzly Creek area a few miles southwest of the Palmer Canyon.
Corundum Corundum has been reported at a number of locations in Wyoming. In addition to the Palmer Canyon deposit, corundum has been reported elsewhere in the Laramie Range, in the Granite Mountains, the Medicine Bow Mountains, Green Mountain, Wind River Mountains, and in the Sierra Madre. Reports of gem-quality corundum are rare in Wyoming although both ruby and sapphire have been reported (Hausel and Sutherland 2000).
Within the Granite Mountains of central Wyoming, are several reported corundum occurrences. One of these, the Red Dwarf deposit, lies northwest of Jeffrey City. The deposit was mapped by the author in 1995, and consists of corundum-bearing quartzofeldspathic gneiss with a strike length of 4,000 feet and widths varying from 20 to 50 feet. The gneiss grades from gray quartzofeldspathic gneiss along its northern end, to chloritic schist along its southern extent. It contains 1-10 percent corundum porphyroblasts partially to completely replaced by fuchsite. The fuchsite typically forms reaction rims encasing the corundum, or may occur as pseudomorphs after corundum. The largest known specimens of Wyoming corundum have been found here. These include red corundum, collected by the author, that was the size of a hen's egg, measuring more than 2 inches across. Another large specimen collected by J. David Love of the US Geological Survey; a fuchsite pseudomorph after corundum (with some preserved purplish-red corundum), measured more than 5 inches in length and 3 inches across.
A few specimens from the Red Dwarf have recently been cut into cabochons, but none have yet been faceted (Robert Odell, pers. com. 1998). These are purplish-red, translucent and cloudy. In addition to the corundum gneiss, a serpentinite found a short distance to the west, contains small (millimeter size), light blue, translucent to opaque corundum (Robert Odell, pers. com 1998). Locally, this rock contains as much as 20 percent corundum (Hausel and Sutherland 2000).

Deep- to purplish-red rubies were described near Sweetwater Divide in central Wyoming. Specimens of this material were cut and polished producing some star-rubies (Curtis 1943) (author’s note: this may be the Red Dwarf corundum deposit located northwest of Jeffrey City in central Wyoming).
Further west, pale-blue and white sapphires are found in mica schist enclosed by gray-brown granite near Sweetwater Station. This deposit, known as the Abernathy prospect, contains abundant 1-inch diameter nodular ‘sapphires’. But for the most part, these are badly shattered and altered around the edges (Love 1970). Pale to bright-red rubies were found in mica schist north of the Abernathy deposit at the Marion prospect. Some of these were cut into gems (Osterwald et al 1966).

Other rubies have been found in float in the Granite Mountains. According to Love (1970), soft green mica schist boulders with dark red rubies were found near Muskrat Creek in the Wind River Formation (Eocene) near Beaver Rim, west of the Gas Hills uranium district, about 12 miles north of the Red Dwarf deposit. These rubies were up to 1 inch in diameter and highly fractured. The source of the schist was not determined. A nearby placer was also reported to contain abundant, bright red (>1 inch in diameter), fractured rubies (Osterwald et al 1966). Chloritic schist float, similar to the Red Dwarf schist, was also found in the Crooks Gap Conglomerate (Tertiary), along the northern flank of Green Mountain, about 15 miles to the southeast of the Red Dwarf (Avon Brock, pers. com 1982; Hausel 1986).

Three flawless iolite gemstones sit on a iolite gneiss from Palmer Canyon. The largest gem weighed more than 0.5 carat

Some corundum was also discovered in the Platt River valley along the edge of the Medicine Bow and Sierra Madre Mountains in southeastern Wyoming. One of these occurs at Baggot's Rock, where specks of corundum are found with kyanite and vermiculite in biotite- and hornblende-schist (Osterwald et al 1966). The deposit was mined for vermiculite from 1937 to 1941 (Hagner 1944).
A few miles south, an open cut in vermiculite hosted by granite-gneiss in the Homestead Draw area, exposed scattered pockets of ruby. Some of these have reaction rims of fuchsite similar to those at the Red Dwarf ruby deposit. Rubies are also reported in another vermiculite to the southwest (Ralph Platt, pers. com 1998).

Abundant industrial corundum with some rubies (including star rubies), are reported in the Big Sandy drainage in the southern Wind River Mountains in western Wyoming (Spendlove 1989). The source of this corundum has not been identified.

Few in situ corundum deposits are known in the Laramie Range of southeastern Wyoming. Even so, some detrital corundum was identified in panned sample concentrates collected in a few drainages during exploration for diamonds in the 1980s (Hausel, Sutherland, and Gregory 1988). There is also a report of purple corundum (0.75 inch in diameter and 4 inches in length) that was found in a granite xenolith in Elk Park a few miles northwest of Palmer Canyon (Ray Harris, pers. com 1992).

Palmer Canyon Deposit
Cordierite was initially discovered in samples collected in Palmer Canyon in 1995, during reconnaissance of corundum-bearing schist. The cordierite was found in quartzofeldspathic gneiss a short distance east of the Roff vermiculite prospect pit, and was later confirmed by XRD analysis (Robert Gregory, pers. com 1996).

The cordierite gneiss crops out over 200 feet, with a width of about 10 feet. The gneiss disappears under soil in every direction from the outcrop, and thus may be more extensive. The presence of detrital cordierite found in soil 300 feet up-slope from the outcrop, suggests that the deposit may have a minimum strike length of 500 feet.

Several samples of cordierite gneiss were collected from the property during initial field investigations. These include transparent cordierite grains that weighed 1.5, 6, 11.5, 13.5, 14, 63.5, 109.5, 308.5, 887, 1,715 and 2,948 carats. Samples collected more recently include a large nodule of facet-grade, violet to blue, massive, transparent cordierite that measured 4.25 x 2.5 x 1.25 inches (>3,000 carats), which is the largest cordierite found in Wyoming, to date. The specimen has several fractures restricting the size of stones that can be cut from the nodule. Some of the gneiss collected from the property contains as much as 20 percent transparent cordierite.

Gem cabochons of kyanite from Palmer Canyon.
Much of the cordierite occurs as rounded to disseminated grains, or as large nodules. A few nodules are inter grown with quartz. In most cases, the strong foliation of the host rock parallels the margins of the nodules, but in a few, the foliation expressed by mica is seen to terminate against one edge of the nodule (i.e., biotite grains are oriented perpendicular to the edge of one surface of the nodule).

The host cordierite gneiss is dark gray to gray cordierite-biotite-sericite-quartz gneiss. Kyanite and sillimanite may also be present, but occur as a minor component of the gneiss. Some secondary calcite may occur as crusts on some surfaces, and many of the cordierite nodules exhibit a very thin (millimeter) zone of alteration along the edge of the nodule that consists of chlorite and sericite.

Three varieties of cordierite were noted. These include: (1) transparent to translucent, violet to blue cordierite with poorly developed parting and cleavage; (2) dark-gray transparent to translucent cordierite with distinct parting and cleavage; and (3) dark-gray, cloudy, translucent to opaque cordierite with common mineral inclusions and distinct parting and cleavage. In the samples collected by the author, variety 1 dominates.

Many specimens of variety 1 appear to be suitable for faceting. This material ranges from a pleasing violet to a very light-blue color and exhibits only a hint of cleavage and parting. A few specimens of variety 1 cordierite were faceted and loaned to the author by Vic Norris. These produced iolite gems with excellent transparency and pleochroism that weighed 0.5, 1.0 and 1.49 carats. Microscopic examination of the 0.5 carat iolite triangular brilliant showed a tiny biotite inclusion that is not visible to the naked eye. The 1.0 carat stone was fashioned into a marquise, and shows several tiny unidentified mineral inclusions under the microscope that are not readily visible to the naked eye. The largest of the three iolites was cut into a modified scissors cut. This stone is clear, but unfortunately has a visible fracture.
Three iolite gems fashioned from 
Palmer Canyon cordierite sit next to 
nodular, transparent cordierite. The 
box containing the iolite gems
 is 0.9 inch across. The nodular iolite
(Palmer Canyon star) was the largest
 iolite gemstone in the world at time of 
its discovery and weighed 1,750 carats.
Later, this stone was dwarfed by the 
Grizzly Creek Blue Giant found by the
 author a few years later in Grizzly 
Creek, which weighed 24, 150 carats.
Even so, samples of massive iolite in 
the outcrop are estimated to weigh 
much greater than 100,000 carats!

Some gray to dark gray cordierite (variety 2) also exhibits excellent transparency. Unfortunately, this variety has well-developed parting parallel to c{001} and cleavage along b{010} limiting the size of facetable material. Many of the gray specimens also exhibit good rectangular cross sections, and a few exhibit pseudohexagonal habit.

Variety 3 cordierite is not suitable for gems as the faceted material has many flaws. Two samples of variety 3 cordierite were faceted. The larger stone weighs 3.9 carats and was faceted into a lozenge-cut stone. The 3.4-carat cordierite was cut with a marquise crown and a step-cut pavilion. Unfortunately, both stones are extensively flawed with fractures, visible cleavage, and some visible mineral inclusions.

Faceted (variety 3) iolite from Palmer
Canyon has too many flaws to produce
good high-quality gems. Next to the
faceted stones are samples of variety 2
rough with well-developed cleavage &
parting (photo by the author).

Corundum. The corundum at Palmer Canyon was also investigated by the author. During the initial investigation, several rock specimens were collected within the old Rolf vermiculite pit, as well as nearby outcrops, and many of these contained some corundum. The corundum is locally abundant, and a few samples contain 15–20 percent corundum.

The schist was traced for nearly 1,000 feet along strike. Samples examined under a binocular microscope show that the corundum-chlorite-biotite schist also contains trace sillimanite and uncommon kyanite. Some spectacular foliated kyanite-mica-schist located adjacent to the corundum schist, exhibits abundant 1– 2-inch-long blades of kyanite. Some of this schist also contains trace corundum.

Some corundum is translucent to transparent, white, pink and less commonly, red. The corundum occurs as porphyroblasts in the schist and forms hexagonal prisms and platelets. The largest specimen collected from the deposit by the author at the time of discovery was 1-inch-long prism with a 0.3-inch diameter. Another broken corundum measured 0.4 inch in diameter. Much of the corundum from this deposit appears to average about 0.2 inch in diameter.

Dark-pink sapphire gem with brownish-
pink sapphire cabochon sit on 
corundum schist from the Palmer 
Canyon deposit (photo by the 

Microscopic examination of the corundum shows the presence of both red ruby and pink to white sapphire. Much of the corundum is transparent to translucent, and only one opaque white to pink corundum was seen in the samples collected during this study.

Two specimens of the corundum were recently fashioned into cut stones. One is a brownish-pink, opaque corundum that was fashioned into a 1.4-carat cabochon. The specimen is pleasing to the eye, but is a near gem of low value. A specimen of dark-pink corundum was also faceted into a transparent, 1.1-carat marquise. This stone exhibits a few minor flaws visible to the naked eye, but otherwise is an attractive gem that was appraised for $300. Three other sapphires were faceted producing gemstones weighing 0.75, 2, and 3 carats (Vic Norris, pers. com 2002).

Fashioned corundum from the Palmer
Canyon deposits surrounded by iolite.
The brownish pink cabochon is translucent
to opaque, while the dark pink marquise
is an attractive transparent gem with
minor flaws (photo by the author).


Until recently, few people considered Wyoming to have potential for gemstones other than nephrite jade. However, during the past few decades, many gemstones were discovered by various prospectors and the author in Wyoming showing that the state to be the most diversified state in the US for variety of gemstones. The variety of gemstones identified by the author include iolite, kyanite, ruby, sapphire, apatite, peridot, pyrope garnet (cape ruby), almandine garnet, spessartine garnet, chrome enstatite, chrome diopside (cape emerald), fire opal, gem opal, onyx, agate, and jasper. Other gemstones discovered since 1975 by other researchers include diamonds, other forms of agate, varisite and common opal.

The possibility of similar deposits to the Palmer Canyon occurrence needs to be addressed, as much of Wyoming’s exposed mountain ranges are cored by amphibolite-grade schists and gneisses. These include large blocks of terrain with metapelites. Some are located only a few miles from the Palmer Canyon occurrence.

Recent field investigations by the author have suggested a possible correlation between corundum and vermiculite: about 10-20 percent of the vermiculite deposits investigated to date, contain some corundum. Thus further investigations of Wyoming’s vermiculite deposits may lead to the discovery of other corundum occurrences. In summary, the presence of additional occurrences of gem-quality corundum and cordierite in Wyoming needs to be seriously considered.


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