QUARTZ

SiO2
Silicon dioxide

 Cleavage: not present

 Colour: variable as the spectrum, but clear quartz is by far the most common color followed by white or cloudy (milky quartz). Purple (Amethyst), pink (Rose Quartz), gray or brown to black (Smoky Quartz)

 Fracture: conchoidal

 Hardness: 7, less in cryptocrystalline forms

 Luster: glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous

 Streak: white

 Possible Useage: silica for glass, electrical components, optical lenses, abrasives, gemstones, ornamental stone, building stone, etc.

 More Info: Mineral Gallery, Mineralogy Database