Peridot

Color: Yellow-green, apple-green, olive/green

Moh’s Hardness: 6.5-7

Refractive Index: 1.654-1.69

Critical Angle: 37.31°

Specific Gravity: 3.27-3.37

Cleavage: Imperfect

Fracture: Brittle, small conchoidal

Dispersion: Moderately high (.02)

Heat Sensitivity: Yes, in my experience

Dichroic: weak

Birefringence (double refraction): Medium (.036)

Crystal Structure: Orthorhombic

Treatments: Generally none, but can be oiled and/or opticoned, if so avoid it