Peridot is the gem-quality olivine mineral. The mineral, olivine, is a silicate, and its crystal structure is made up of single isolated tetrahedron crystals. This tetrahedron shapehas the same shape as Peridot's hair. Peridot is the birthstone of August, along with Sardonyx.

Color Green, Yellow
Mohs scale hardness 7.0
Specific gravity 3.22 - 3.45
Refractive index 1.635 - 1.690