Moldavite
Moldavite is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany that occurred about 15 million years ago. It is a type of tektite and a gemstone. Wikipedia
Category: Glass
Color: Olive green
Crystal system: Amorphous
Luster: Vitreous
Optical properties: Isotropic
Refractive index: 1.48 to 1.54
Specific gravity: 2.32 to 2.38