Wyoming Jade
Wyoming Jade
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The term jade is applied to two distinct and unrelated mineral species. Jadeite is composed of fine-grained, compact massive aggregates of interlocking pyroxene crystals in the augite series. Although minor jadeite has been reported in northwestern Wyoming, its occurrence has never been verified. Nephrite comprises extremely dense and compact, fine-grained, felted, fibrous amphibole crystals in the tremolite-actinolite series. Positive distinction between the two jades often requires the aid of tests such as petrographic, specific gravity, geochemical, and/or X-ray diffraction analyses.
Wyoming Jade is nephrite. Sinkankas (1959) considered Wyoming Jade to be some of the finest nephrite in the world. Nephrite is a calcium magnesium silicate varying in composition from actinolite to tremolite. Variations in chemistry are responsible for a wide range of colors extending from white to black, with rare occurrences of blue and off white. However, most common nephrite jade is of varying shades of green, such as apple, emerald, leaf, and olive. The green color is attributed to the presence of reduced iron, with varying contributions from other elements.
Jade window dominated by Wyoming Jade in the North Shore Baptist Church, Chicago, IL, built by James L. Kraft in 1952. [Credit: R.D. Locke]
Wyoming Jade. [Credit: Wayne M. Sutherland, WSGS]
The translucent jade window at the North Shore Baptist Church in Chicago, Illinois, illustrates some of the colors found in Wyoming Jade. The window is 6.5 feet high and 3.5 feet wide, and was dedicated in 1952. James L. Kraft, president of the Kraft Foods Company in Chicago and an avid collector of Wyoming Jade, made it for the church. The jade came primarily from Wyoming, with the wide variety of greens, blues, and other unusual colors of jade resulting from years of searching across the central part of the state by Mr. and Mrs. Allan Branham of Lander, Wyoming. Some of the jade also came from Alaska, Arizona, and California.
Delicately carved jadeite figure from China. [Credit: Wayne M. Sutherland, WSGS]
Hardness/Durability
Hardness/Durability
Nephrite’s hardness, combined with its micro-felted aggregate structure, makes it relatively easy to saw and carve into delicate but extremely durable objects. This durability is a major factor behind Wyoming Jade’s high reputation. Nephrite has a moderate hardness of 5.5 to 6.5 on the Mohs scale, which has a range of 1 being the softest and 10 being the hardest. Because of its micro-fibrous aggregate structure, nephrite has no cleavage; if broken, it exhibits an irregular splintery fracture with a dull surface unless accompanied by inclusions of other minerals such as mica. Nephrite may occasionally show a direction of separation or schistosity due to mineral inclusions and may also host fine fractures related to tectonic movement. Either of these conditions drastically reduce the quality of the jade.
Quality
Quality
Jade quality is based upon uniformity of texture and lack of inclusions coupled with color intensity and translucency. Wyoming Jade varies from translucent to opaque. Most nephrite contains some inclusions, which can affect its ability to take a polish. Lighter and brighter colors are rarer and are generally valued more highly than darker colors. Similarly, more translucent nephrite commands higher prices than nearly opaque material. These factors and their interrelationships determine the overall assessment of an individual piece of jade. Finished pieces of high-quality material vary upward from a few carats to many kilograms. Only about 10 percent of most nephrite deposits are considered gem quality.
The durability of jade, when lacking inclusions or fractures, makes it extremely resistant to erosion. High-quality nephrite is much more resistant than either low-quality jade or the rocks that enclosed it where it formed. Most of the high-quality jade found in Wyoming has been extracted from alluvial deposits in and around the Granite Mountains of central Wyoming. In fact, detrital nephrite jade is found over a wide area extending from the southern end of the Wind River Mountains on the west, to the Platte River near the town of Guernsey on the east, and from Sage Creek Basin along the Sierra Madre on the south, to near the town of Lysite on the north. Jade’s specific gravity of 2.9 to 3.02 is not great enough to concentrate into well-defined placers.
Rocks and Minerals Similar to Nephrite Jade
Rocks and Minerals Similar to Nephrite Jade
Several rocks and minerals have been mistaken for nephrite jade and can be distinguished by hardness, physical appearance, or X-ray diffraction. These include serpentine, serpentinite, amphibolite, metadiabase, leucocratic granite, epidote, and fuchsitic quartzite. The lack of granular structure in nephrite easily distinguishes it in rough pieces from rocks such as metadiabase, amphibolite, and leucocratic granite. A freshly broken surface of quartzite tends to sparkle in the sunlight off of individual quartz grains and conchoidal fractures, which are notably different than nephrite. Epidote has a perfect cleavage and pistachio-green color not found in nephrite. Serpentinite is relatively soft and can often be easily scratched with a knife, and contains zones that are weakly to moderately magnetic; all characteristics not found in jade.
Common Measures for Gemstones Chart
Common Measures for Gemstones Chart
Wyoming Jade References and Recommended References
Wyoming Jade References and Recommended References
Further information about Wyoming Jade can be found in the following WSGS publications:
For a complete listing of WSGS materials, go to the Online Catalog.
Jade References
Bagdonas, D.A., 2014, Petrogenesis of the Neoarchean Wyoming batholith, central Wyoming: Laramie, University of Wyoming, M.S. thesis, 120 p., 1 pl.
Barnes, L.C., Flint, D.J., and Dubowski, T., 1987, World review of nephrite jade—Geology, production, and reserves: South Australia Department of Mines and Energy, Rept. Bk. No. 87/116, 48 p., 12 tables, 6 figs.
Bauer, Max, 1969, Precious Stones: Charles E. Tuttle Company, Rutland, VT, and Tokyo, Japan, 647 p.
Bergsten, L.J., 1964, History of the Wyoming Jade region: Lapidary Journal, September 1964, Reprinted in MacFall, Russell P., ed., undated, Wyoming Jade—A Pioneer Hunter’s Story: Self published, 56 p.
Bishop, D.T., 1964, Retrogressive metamorphism in the Seminoe Mountains, Carbon County, Wyoming: Laramie, University of Wyoming, M.S. thesis, 49 p., scale 1:24,000.
Branham, A., 1941, Jade found in Wyoming: The Mineralogist, v. 9, no. 3, p. 79–80.
Branham, A., 1965 and 1966, Several articles in MacFall, Russell P., ed., undated, Wyoming Jade—A pioneer hunter’s story: Self published, 56 p.
Chamberlain, K.R., and Frost, B.R., 1995, Mid-Proterozoic mafic dikes in the central Wyoming Province—Evidence for Belt-age extension and supercontinent breakup: Geological Association of Canada—Mineralogical Association of Canada annual conference, Abstracts, v. 20, p. A-15.
Chamberlain, K.R., Frost, C.D., and Frost, B.R., 2003, Early Archean to Mesoproterozoic evolution of the Wyoming Province – Archean origins to modern lithospheric architecture: Canadian Journal of Earth Sciences, v. 40, no. 10, p. 1,357–1,374.
Chamberlain, K.R., Sears, J.W., Frost, B.R., and Doughty, P.T., 2000, Ages of Belt Supergroup deposition and intrusion of mafic dikes in the central Wyoming Province—Evidence for extension at ca. 1.5 Ga and 1.37 Ga and potential piercing points for Rodinia reconstructions: Geological Society of America, Abstracts with Programs, v. 32, no. 7, p. A-319.
Dake, H.C., 1942, Jade in Wyoming—New discoveries: The Mineralogist, v. 10, no. 9, p. 275–276.
Frost, C.D., Frost, B.R., Chamberlain, K.R., and Hulsebosch, T.P., 1998, The Late Archean history of the Wyoming Province as recorded by granitic magmatism in the Wind River Range, Wyoming, Precambrian Research, v. 89, p. 145–173.
Frost, C.D., Fruchey, B.L., Chamberlain, K.R., and Frost, R.B., 2006, Archean crustal growth by lateral accretion of juvenile supracrustal belts in the south-central Wyoming Province: Canadian Journal of Earth Sciences, v. 43, p. 1,533–1,555.
Fruchey, B.L., 2002, Archean supracrustal sequences of contrasting origin—The Archean history of the Barlow Gap area, northern Granite Mountains, Wyoming: Laramie, University of Wyoming, M.S. thesis, 178 p., scale 1:24,000 and 1:3,000.
Grace, R.L.B., Chamberlain, K.R., Frost, B.R., and Frost, C.D., 2006, Tectonic histories of the Paleoarchean to Mesoarchean Sacawee block and Neoarchean Oregon Trail structural belt of south-central Wyoming Province: Canadian Journal of Earth Sciences, v. 43, no. 10, p. 1,445–1,466..
Harlow, G.E., and Sorensen, S.S., 2001, Jade: Occurrence and metasomatic origin—Extended abstract from International Geological Congress 2000: The Australian Gemmologist, v. 21, p. 7–10.
Hausel, W.D., and Holden, G.S., 1978, Mineral resources of the Wind River Basin and adjacent Precambrian uplifts: Wyoming Geological Association 13th Annual Field Conference, Guidebook, p. 303–310.
Hill, Robert Sr., 1979, Nephrite, jadeite—jade: Gems & Minerals Magazine, no. 504, p. 62.
Hurlbut, C.S., and Switzer, G.S., 1979, Gemology: John Wiley & Sons, New York, NY, 252 p.
Kraft, J.L., 1947, Adventure in jade: Holt and Company, 81 p.
Langstaff, G.D., 1995, Archean geology of the Granite Mountains: Golden, Colorado School of Mines, Ph.D. dissertation, 671 p., 9 pls., scale 1:24,000 and 1:100,000.
Love. J.D., 1945, Jade deposits in central Wyoming: Unpublished partial draft, 5 p.
Love. J.D., 1970, Cenozoic geology of the Granite Mountains area, central Wyoming: USGS Professional Paper 495-C, p. C1-C154, scale 1:125,000.
Ludwig, K.R., and Stuckless, J.S., 1978, Uranium-lead isotope systematics and apparent ages of zircons and other minerals in Precambrian granitic rocks, Granite Mountains, Wyoming: Contributions to Mineralogy and Petrology, v. 65, p. 243-254.
MacFall, R.P., ed., undated, Wyoming Jade—A Pioneer Hunter’s Story: Self-published, 56 p.
Madsen, M.E., 1978, Nephrite occurrences in the Granite Mountains region of Wyoming: Wyoming Geological Association 13th Annual Field Conference Guidebook, p. 393–397.
Peterman, Z.E., and Hildreth, R.A., 1978, Reconnaissance geology and geochronology of the Precambrian of the Granite Mountains, Wyoming: U.S. Geological Survey Professional Paper 1055, 22 p.
Rhoads, Verla, 1969, History on Wyoming Jade: unpublished, 6 p.
Sanders, G.V., 1945, Green gold of Wyoming: Popular Science, v. 146, no. 2, p. 112–114, 208.
Sherer, R.L., 1969, Nephrite deposits of the Granite, Seminoe, and Laramie mountains, Wyoming: Laramie, University of Wyoming, Ph.D. dissertation, 194 p., 30 pls.
Sinkankas, John, 1959, Gemstones of North America: Van Nostrand Company, Inc., New York, NY, 675 p.
Sutherland, W.M., 2010, The discovery of Wyoming Jade: Jade State News, v. 2010, is. 2, p. 2–3.
Wall, E.N., 2004, Petrologic, geochemical and isotopic constraints on the origin of 2.6 Ga post-tectonic granitoids of the central Wyoming Province: Laramie, University of Wyoming, M.S. thesis, 185 p.
Ward, F., 1999, World jade resources: Arts in Asia, v. 29, no. 1, p. 68–71, in Gemological Abstracts, Gems and Gemology, Summer 1999, v. 35, no. 2, p. 163.
Ward, F., 2001, Jade: Gem Book Publishers, Bethesda, MD, 64 p.
Contact:
Christopher Doorn, christopher.doorn@wyo.gov
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