Thursday, October 4, 2012

Gemstone of the Week: Dravite

(Dravite image found on; custom faceted gemstone by Michiko Huynh)

Dravite is one of the many little known varieties of Tourmaline.  It is generally light to dark brown, but may also be brownish-black, dark yellow, blue, red, green, or white. It is a hardness 7 with a vitreous to resinous luster and may be transparent to translucent. Dravite was discovered in 1883 and was named after the Drau river ("Drave" in Latin) where it was first discovered.  As with all Tourmaline, Dravite can reach very high prices, although inexpensive specimens are available.  Dravite has a trigonal crystal structure, and is most often found in metamorphosed limestones or mafic igneous rock. It can, however, on the rare occasion be found in pegmatites or authogenic overgrowths in sedimentary rocks.  Dravite may be found in: Antarctica, India, Australia, Madagascar, Namibia, South Africa, Mozambique, Tanzania, Nepal, Iran, Burma/Myanmar, China, Afghanistan, Tajikistan, Russia, North Korea, Japan, Sweden, Finland, the UK, Italy, Spain, France, Germany, Poland, Slovenia, Hungary, Slovakia, Czech Republic, Austria, Peru, Chili, Bolivia, Brazil, and numerous locations across both the U.S. and Canada.