Peridot in basalt bombs. Tucson Gem Shows;
photo by S.W. Aber, 4/2008.
GO 340 Gemstones & Gemology
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|Peridot (pronounced pear-a-doe) is the gem variety of the mineral olivine, and also called chrysolite. It is a magnesium iron silicate, (Mg, Fe)2SiO4, with a hardness of 6.5-7, and specific gravity of 3.28-3.48. Cleavage is indistinct and the fracture, conchoidal. Crystal form is rare, although it is in the orthorhombic crystal system. It is doubly refractive with refractive indices of 1.63 and 1.695 (Amethyst Mineral Galleries, 1995-2012). Pleochroism is weak and peridot has no fluorescence.|
|Peridot was mined for over 3,500 years on the volcanic island of Zebirget, or St. Johns Island, in the Red Sea, and the deposits rediscovered in 1900. It is also found in Myanmar (Burma), Arizona, New Mexico, and Hawaii, in the US, China, Pakistan, Norway, Brazil, Australia, Kenya, Mexico, Sri Lanka, South Africa, and Tanzania. The United States was one of the largest producers of peridot, with an estimated value of production of $1.5 million in 1999 (Jewelry Central, 1999-2012). In addition to being recovered from igneous basalt, gabbro, and peridotite, peridot also occurs in certain types of meteorites.||
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|Left two images taken from Gem Hut||Center image taken from |
|Right two images taken from Gem Hut|
Peridot is the birthstone for August and 16th anniversary gem (Jewelry Central). It was probably called "emerald" in ancient accounts and Romans termed it "evening emerald." Peridot was one of the twelve stones in the the high priest's breastplate in the Biblical book of Exodus. This gem, in a powdered form, was to cure asthma and believed to lessen the effects of enchantment.
<<< Image left taken from Mineral Galleries.
The largest cut peridot is 310 carats and housed at the Smithsonian in Washington, D.C.; a 192.75 carat stone belonging to czars is in the Diamond Treasury, Moscow; and a 146 carat peridot may be found in the Geological Museum in London, England (CW Jewelers, 1999). It is a relatively inexpensive gemstone in small sizes, but the value goes up with stones over 5 carats, with 10-15 carat stones very rare and expensive.
Image right is faceted peridot courtesy of GIA Educational Images © Gemological Institute of America. >>>
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- Amethyst Mineral Galleries (1997-2012). http://www.galleries.com/minerals/gemstone/peridot/peridot.htm
- Coyle Wholesale Jewelers (1999). http://www.cwjewelers.com/stoneperidot.htm
- Gem Hut (1995-2012). http://www.gemhut.com/peridot.htm
- Jewelry Central (1999-2012). http://www.jewelrycentral.com/Target_Peridot.asp
- The Image (1996-2007). http://www.theimage.com/gemstone/peridot/peridot.html
- Michael Sedlacek on Peridot, http://www.emporia.edu/earthsci/amber/go340/students/sedlacek/
- USGS Peridot. http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/peridot.html.
- Buyers Guide to Peridot. http://www.jewelrymall.com/stones/peridot.html.
- International Colored Gemstones, Peridot: The Extraterrestrial Gem, http://www.gemstone.org/gem-by-gem/english/peridot.html.
This page originates from the Earth Science department for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: email@example.com Thanks for visiting! Webpage created: November 15, 2000; last update: August 30, 2012.Copyright 1999-2012 Susan Ward Aber. All rights reserved.