Moldavite (silicon dioxide + aluminum oxide)
Color: Bottle-green to brownish-green.
Moh’s hardness: 5.5
Refractive index: 1.48-1.5
Critical angle: 42.5°
Specific gravity: 2.32-2.38
Heat sensitivity: Moderate
Birefringence (double refraction): None
Crystal structure: Amorphous
Cutting: Moldavite is basically glass and cuts easily.
Polishing: Cerium oxide on most common polishing laps.
Comments: Moldavite is said to be a tektite, created when a large meteor crashed into the earth with such force that it propelled material outside of the atmosphere. This material fell back to the earth in what is now the the Czech Republic. It is common for moldavite to contain small bubbles.