CLASS: Nesosilicate . . . CHEMICAL FORMULA: (Mg,Fe)2 (SiO4) . . . CRYSTAL SYSTEM: Rhombic
CRYSTAL FORM: prism, pinacoid, rhombic bipyramid; rounded corners
It comprises an isomorphic series from Forsterite (Mg2 (SiO4)) to Fayalite (Fe2 (SiO4)).
COLOR: olive green or yellowish, brown, red.
The transparent green variety is called Peridot, used as a gem.
PHYSICAL PROPERTIES: hard (6.5/7 Mohs), heavy (3.30/4.20 g/cm3), increasing density to a higher proportion of Iron (Fe), fragile, with conchoidal fracture, transparent/translucent, vitreous/greasy luster.
Olivines rich in Magnesium are characteristic of magmatic rocks. It is also present in some Meteorites and in rocks of the Moon.
CURIOSITIES: it is related to the power of regeneration, leaving behind the negative.