Olivine (Forsterite (Mg) and Fayalite (Fe))Mg2SiO4 - Fe2SiO4|
Hardness: 6.5 - 7
Density: 3.3 - 4.3
Colours: Pistachio green, greenish yellow brown
| ||Crystal System: Orthorhombic|
Reaction with HCl: Very weak
Identification in hand sample:
Pistachio-green colour and granular habit.
Mafic and ultramafic igneous rocks. Associated with Ca-plag,
Industrial / ecomonic uses:
Peridote (a translucent variety of olivine) is considered a 'gem' mineral. Also used as a refractory sand and infrequently as an abrasive.
Complete solid solution exists between the magnesium-rich end member (Forsterite, Mg2SiO4) and the iron-rich end member (Fayalite, Fe2SiO4).