Quartz

All data from the card 23

Category: Oxide mineral
Chemical formula: Silica (silicon dioxide, SiO2)
Strunz classification: 04.DA.05
Dana classification: 75.01.03.01
Color: Colorless through various colors to black
Crystal habit: 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive
Crystal system: α-quartz: trigonal trapezohedral class 3 2; β-quartz: hexagonal 622
Twinning: Common Dauphine law, Brazil law and Japan law
Cleavage: {0110} Indistinct
Fracture: Conchoidal
Tenacity: Brittle
Mohs scale hardness: 7 - lower in impure varieties
Luster: Vitreous - waxy to dull when massive
Streak: White
Diaphaneity: Transparent to nearly opaque
Specific gravity: 2.65; variable 2.59 - 2.63 in impure varieties
Optical properties: Uniaxial (+)
Refractive index: nω = 1.543 - 1.545 nε = 1.552 - 1.554
Birefringence: +0.009 (B-G interval)
Pleochroism: None
Melting point: 1670 °C (β tridymite) 1713 °C (β cristobalite)
Solubility: 1 ppmmass at 400 °C and 500 lb/in2 to 2600 ppmmass at 500 °C and 1500 lb/in2
Other characteristics: Piezoelectric, pyroelectric, may be triboluminescent

Quartz

In 102 languages

Text from Wikipedia, CC BY-SA 4.0 · Source article