Olivine

n. mineral compound of magnesium iron silicate which usually has an olive-green color

The mineral olivine (also called chrysolite and, when gem-quality, peridot) is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. It is one of the most common minerals on Earth, and has also been identified on the Moon, Mars, and comet Wild 2. The ratio of magnesium and iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember) and fayalite (Fe-endmember). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (e.g., Fo70Fa30). Forsterite has an unusually high melting temperature at atmospheric pressure, almost 1900°C, but the melting temperature of fayalite is much lower (about 1200°C). The melting temperature varies smoothly between the two endmembers, as do other properties.
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Noun
1. a mineral consisting of magnesium iron silicate; a source of magnesium
(hypernym) mineral
(hyponym) chrysolite
(substance-meronym) magnesium, Mg, atomic number 12

n. olivine, mineral

n. olivine, mineral compound of magnesium iron silicate which usually has an olive-green color