Quartz

Quartz
Chemical name	Silicon dioxide
Chemical formula	SiO2
Identification
Colors	Clear (with no impurities)
Crystal habit	6-sided prism ending in 6-sided pyramid
Crystal system	rhombohedral
Cleavage	None
Fracture	Conchoidal
Hardness	7
Name origin	German "Quarz".
Specific gravity	2.65
Streak	White

Quartz is the second most common mineral found on Earth being the primary component of sand. More accurately known as silicon dioxide, quartz has a chemical composition of SiO₂ arranged in a repeating lattice forming hexagonal crystals. Pure quartz is clear, but colored variations are created because of impurities in the crystal. Quartz is number 7 on the Mohs Hardness Scale.
Quartz is used in a number of applications; most commonly in glass making but also abrasives, electrical components or decorative gemstones especially if colored by impurities.