Description

Opal forms in cracks or cavities in volcanic rocks, in deposits from hot springs, and in sediments. It has no crystalline structure (no regular arrangement of atoms). Instead, chains of silicon and oxygen are packed into tiny spheres. Diffraction of light by these spheres produces the multicolored flashes of light (play of color) that give the stone its beauty. “Potch”, or common Opal, has a milky appearance and does not exhibit a play of color. In the Middle Ages, Opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal. Precious opal is found in Australia, Ethiopia and Idaho. Pink (Andean) Opal is found in Peru. Opal is the October birthstone.