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Agate, along with carnelian, chrysoprase, jasper, and flint, is a variety of chalcedony, a type of quartz made up of tiny crystalline fibers. Agate has a striking color banding due to slight differences in the compositions and grain sizes of the crystalline fibers. Class: semiprecious Origin of Name: from the Latin achates, the former name of Sicily's river Drillo, along which agate was found in ancient times Color: green, yellow, red, reddish-brown, white, bluish-white Chemical Composition: silica Crystal System: trigonal (microcrystalline) Hardness: 6.5 Specific Gravity: 2.57-2.64 Geographic Origins: worldwide but chiefly Brazil and Uruguay 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 |