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Tourmaline shows the greatest range of colors of any gem and its varieties of composition led the Victorian thinker John Ruskin to write that "the chemistry of it is more like a medieval doctor's prescription than the making of a respectable mineral." Class: semiprecious Origin of Name: from the Sinhalese tourmali (mixed stones) Color: most colors, most popularly pink and green Chemical Composition: complex silicate of boron and aluminum Crystal System: trigonal Hardness: 7-7.5 Specific Gravity: 3.0-3.25 Geographic Origins: Namibia, Zambia, Nigeria, Russia, Brazil, Maine, North Carolina, California Next Photo: ©International Colored Gemstone Association/Bart Curren The Science Behind the Sparkle | Diamonds in the Sky A Primer of Gemstones | See Inside a Diamond Resources | Transcript | Site Map | Diamond Deception Home Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated November 2000 |