Quartz is the seicont maist abundant meeneral in the Yird's continental crust, efter feldspar. It is made up o a conteenous framework o SiO4 silicon–oxygen tetrahedra, wi lika oxygen bein shared atween twa tetrahedra, giein an oweraw formula SiO2.
| Quartz | |
|---|---|
 Quartz creestal cluster frae Tibet | |
| General | |
| Category | Silicate mineral |
| Formula (repeatin unit) | SiO2 |
| Strunz clessification | 04.DA.05 |
| Dana clessification | 75.01.03.01 |
| Creestal seestem | α-quartz: trigonal trapezohedral class 3 2; β-quartz: hexagonal 622[1] |
| Space group | Trigonal 32 |
| Unit cell | a = 4.9133 Å, c = 5.4053 Å; Z=3 |
| Identification | |
| Colour | Colourless through various colours tae black |
| Creestal habit | 6-sidit prism endin in 6-sided pyramid (typical), drusy, fine-grained tae microcrystalline, massive |
| Twinnin | Common Dauphine law, Brazil law an Japan law |
| Cleavage | {0110} Indistinct |
| Fractur | Conchoidal |
| Tenacity | Brickle |
| Mohs scale haurdness | 7 – lawer in impure varieties (definin mineral) |
| Skinkle | Vitreous – waxy tae dull when massive |
| Streak | White |
| Diaphaneity | Transparent tae near opaque |
| Speceefic 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 |
| Meltin pynt | 1670 °C (β tridymite) 1713 °C (β cristobalite)[1] |
| Solubility | Insoluble at STP; 1 ppmmass at 400 °C an 500 lb/in2 tae 2600 ppmmass at 500 °C an 1500 lb/in2[1] |
| Ither chairacteristics | Piezoelectric, mey be triboluminescent, chiral (hence optically active if nae racemic) |
| References | [2][3][4][5] |
Thare mony different varieties o quartz, several o whilk is semi-precious gemstones. Ispecially in Europe an the Middle East, varieties o quartz haes been syne antiquity the maist commonly uised meenerals in the makkin o jewelry an hairdstane carvins.
The wird "quartz" is derived frae the German wird "Quarz" an its Middle Heich German auncestor "twarc", that belike oreeginatit in Slavic (cf. Czech tvrdý ("haird"), Pols twardy ("haird")).[6]
References
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