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| Faceted (transparent red) and cabochon (opaque cab) rubies sitting on specimen of corundum vermiculite schist collected in Palmer Canyon (photo by the author. Gems weigh a little more than 1-carat each. |
Corundum exhibits a variety of colors including gray, grayish green, blue, pink, brown, red & purple. Some corundum is used to produce extraordinary gemstones. Ruby is the deep pigeon’s-blood red translucent to transparent variety of corundum with adamantine luster and sapphire includes all other colors.
It will display a striking adamantine to vitreous luster noticeable in faceted gemstones. High specific gravity (4 to 4.1) is favorable for its concentration in black sand concentrates in streams. During sampling in the central Laramie Range, we recovered tiny rubies and sapphires in several sample concentrates in that region, suggesting that several corundum deposits remain to be discovered.
Palmer Canyon ruby mounted in necklace (photo courtesy of Chuck Mabarak) & showing parting (right - note the distinct lines in the gemstone).THE CORUNDUM GEMSTONES include a variety of colors including:
Red Ruby
Cornflower Blue Sapphire
Colorless Leuco-sapphire
Light bluish-green Oriental Aquamarine
Green Oriental Emerald
Yellow-Green Oriental Chrysolite
Yellow Oriental Topaz
Aurora Red Oriental Hyacinth
Violet Oriental Amethyst
Occurrence. Corundum, a high-pressure aluminum oxide, is found with silica-poor, aluminum-rich metamorphic rocks in often referred to as metapelite, mica schist and hornfels.
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| Ruby with parting from undisclosed location in WY |
Metapelite may contain a variety of alumino-silicate porphyroblasts such as mica, kyanite, sillimanite, andalusite, vermiculite & cordierite. The corundum itself is typically found in vermiculite schist and aluminum-rich serpentinites. Vermiculite schist is considered an alteration product of a former metapelite in which metapelite was desilicated leaving mica-rich rock known as vermiculite schist or glimmerite schist. After noting the close association of vermiculite & ruby, I discovered several more ruby deposits in Wyoming. This was also true of iolite and pelitic schist. Using geology proved to be extremely valuable.
Localities. Corundum has been found at a number of places in Wyoming. Wyoming could easily develop a major ruby and sapphire industry along with many other commodities - such as diamond, gold, palladium, rare earths, iolite, labradorite, copper, zinc and silver - but its political regime with the US Forest Service have worked for more than 30 years to withdraw nearly all non-energy mineral resources from public lands - something that should be considered illegal. Over the years, we provided evidence for major and world-class mineral deposits and several companies found significant base metal deposits, only to find government interference at every level.
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| Large ruby-zoisite porphyroblast from Red Dwarf deposit found by J. David Love of the US Geological Survey. Much of this giant ruby was replaced by zoisite, but excellent pigeon’s blood red ruby remains untouched. Prior to replacement, this specimen would have been one of the largest rubies in the world. It suggests that large rubies remain to be found at the Red Dwarf. |
One interesting locality lies northwest of Jeffrey City, known as the Red Dwarf deposit (sections 13 and 24, T30N, R93W), was investigated by me several years ago. The deposit consists of corundum gneiss & schist with a 5,000 foot strike length with widths of 20 to 50 feet. The rock has 1 to 10% corundum porphyroblasts encased in zoisite-fuchsite reaction rims and considerable fuchsite and zoisite pseudomorphs after corundum. Where found, some of corundum is translucent with good color.
The corundum may be light purplish-pink, lavender, to reddish-purple, and range from millimeter size to more than two inches across. Some gem-quality corundum was found in the past and partially replaced specimens provide evidence for rubies of five inches (or more) in length and more than 2 inches in diameter.
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| Beautiful specimen of reddish-purple corundum (variety - ruby) collected by Eric Hausel from the Red Dwarf deposit, Granite Mountains, Wyoming (photo by Robert Odell). |
A nearby serpentinite discovered west of the ruby schist contains tiny (millimeter size), light-blue, translucent to opaque corundum. Locally, the serpentinite has 20 to 40% corundum.
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| Palmer Canyon corundum schist showing some pink corundum (var. sapphire) enclosed within blue kyanite in the vermiculite schist (photo by the author). |
At another deposit known as the Abernathy deposit (section 26, T30N, R96W) near Sweetwater Station, pale-blue and white corundum is found in mica schist. The corundum is abundant and occurs as one-inch diameter nodules in the schist.
Corundum is also associated with vermiculite schist (glimmerite) west of Wheatland in Palmer Canyon. This deposit (N/2 Section 18, T24N, R70W) is associated with kyanite, cordierite, and sillimanite schist and gneiss. The corundum forms small, hexagonal, pink, red and white grains from about 0.1 to 0.3 inch across. Many grains have well-developed parting which limits the size of facetable material. Even so, significant percentages have excellent color, and are transparent to translucent (Personal field notes, 1997). Locally, the schist may contain >20% corundum. Small amounts of corundum have also been identified at the Grizzly Creek iolite (cordierite) deposit to the south and other localities to the north.
Some corundum was identified in vermiculite schist in the Platte River Valley between the Medicine Bow and Sierra Madre Mountains. Another notable corundum locality is in the Big Sandy opening along the southern margin of the Wind River Mountains, where hundreds of corundum crystals weighing up to 90 carats have been collected from Squaw Creek by prospectors (Russ and Joe Sims, personal communication). The source of this corundum remains undiscovered. Some nearby ruby schist float was found (B.F. Frost, Personal communication) indicating the presence of ruby deposit. According to Dr. Frost, this ruby deposit is widespread within the southern core of the Wind River Mountains. Location, however, could not be verified and may be erroneous.
Below - Raw translucent pink sapphire from Palmer Canyon. Below right - faceted pink sapphires & blue iolites from Palmer Canyon, & Below far right - large raw ruby from the Rattlesnake Hills, Wyoming. In addition to these stones, the author was following rubies near the Big Sandy opening in the Wind River Mountains, the Rattlesnake Hills, Barlow Gap, the Sierra Madre, the central Laramie Range & the Saratoga valley.
