Olivine occurs in several varieties that range in composition from magnesium silicate (forsterite) to iron silicate (fayalite) to calcium magnesium silicate (monticellite). Olivine is a mineral found in the oceanic crust and upper mantle, and is primarily stable at higher pressures and temperatures. It is commonly found in masses of small crystals or as individual crystals in a basalt.
Pronunciation: OL•iv•een (accent on capitalized syllable)
Color: varies with composition, but generally olive green
Luster: glassy
Diaphaneity: transparent to translucent; some specimens may appear to be opaque in hand specimen
Hardness: 6.5-7
Specific gravity: 3.27-4.37, increasing with iron content
Cleavage/fracture: fractures along irregular surfaces
Other distinguishing properties: Olivine commonly looks like a small piece of broken green glass within a rock. Crystals tend to be roughly the same length in all directions (equant) or slightly elongated in one direction.
Klein, C., and Hurlbut, C.S., Jr., 1999, Manual of Mineralogy (after James D. Dana) [21st edition, revised]: New York, John Wiley & Sons, 682 p.
Los Angeles County Museum of Natural History, The Photo Atlas of Minerals: nhm.org/pam/
Return to the Minerals page.
