Wednesday, January 23, 2013

Gemstone of the Week: Scheelite

(Scheelite image found on carnegiemnh.org)

Scheelite was in 1821 and is named after Swedish chemist Karl Wilhelm Scheele who proved the existence of tungstic oxide in 1781. Scheelite is a calcium tungstate and has a hardness of 4.5-5.  It may be tan, golden-yellow, colourless, white, greenish, dark brown, reddish yellow, pale yellow, and otehr various shades of these colours.  In transmitted light, Scheelite will appear colourless.  Scheelite may even form with colour-zoning. It has an adamantine to vitreous luster, and may be transparent or opaque. Scheelite may be found in contact-metamorphic tactites, high temperature hydrothermal veins and greisens, granitic pegmatites, or alluvial deposits.  It has a dipyramidal, tetragonal crystal structure. Scheelite is may be found all over the world in: Afghanistan, Algeria, Argentina, Armenia, Australia, Austria, Belgium, Bhutan, Bolivia, Brazil, Bulgaria, Burma(Myanmar), Cambodia, Chile, China, Czech Republic, Democratic Republic of Congo(Zaire), Ecuador, Finland, France, Georgia, Germany, Greece, Greenland, Guatemala, Guyana, India, Hungary, Indonesia, Iran, Ireland, Italy, Japan, Kazakhstan, Kosovo, Kyrgyzstan, Madagascar, Malawi, Malaysia, Mexico, Mongolia, Morocco, Mozambique, Niger, Namibia, New Zealand, North Korea, Norway, Pakistan, Peru, Philippians, Portugal, Poland, Republic of Macedonia, Romania, Russia, Rwanda, Serbia, Saudi Arabia, Slovakia, South Africa, South Korea, Spain, Sri Lanka, Sudan, Swaziland, Sweden, Tajikistan, Tanzania, Thailand, Turkey, Uganda, the U.K, Ukraine, Uzbekistan, Venezuela, and Zambabwe and all across Canada and the U.S. you could also say that Scheelite is 'out of this world' as it can also be found on the moon!