Chalcedony Rock Professor Image

Chalcedony is a mineral composed of microscopic crystals of quartz. It is a cryptocrystalline form of silica, thus the crystals are too small to be seen without a microscope. Chalcedony is used in jewelry making, industrial and geology applications.

Species: quartz - variety of chalcedony ♦ Chemistry: silicon dioxide ♦ Color: white, grey, blue, pink, yellow, brown, red, black ♦ Cleavage: none ♦ Fracture: conchoidal ♦ Transparency: translucent to opaque ♦ Luster: waxy to dull ♦ Crystal System: none ♦ Moh's Hardness: 6.5-7 ♦ Localities: Brazil, Madagascar, Mexico, USA.