පළිඟු |
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Quartz crystal cluster from Tibet |
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Category | Silicate mineral |
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රසායනික සූත්රය | SiO2 |
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Strunz classification | 04.DA.05 |
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Dana classification | 75.01.03.01 |
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Crystal symmetry | Trigonal 32 |
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Unit cell | a = 4.9133 Å, c = 5.4053 Å; Z=3 |
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පාට / පැහැය | Colorless through various colors to black |
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Crystal habit | 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive |
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Crystal system | α-quartz: trigonal trapezohedral class 3 2; β-quartz: hexagonal 622[1] |
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Twinning | Common Dauphine law, Brazil law and Japan law |
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Cleavage | {0110} Indistinct |
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Fracture | Conchoidal |
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Tenacity | කැඩෙනසුළු |
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Mohs scale hardness | 7 – lower in impure varieties (defining mineral) |
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Luster | Vitreous – waxy to dull when massive |
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Streak | සුදු |
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Diaphaneity | Transparent to nearly opaque |
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Specific gravity | 2.65; variable 2.59–2.63 in impure varieties |
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Optical properties | Uniaxial (+) |
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Refractive index | nω = 1.543–1.545 nε = 1.552–1.554 |
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Birefringence | +0.009 (B-G interval) |
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Pleochroism | නැත |
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Melting point | 1670 °C (β tridymite) 1713 °C (β cristobalite)[1] |
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Solubility | Insoluble at STP; 1 ppmmass at 400 °C and 500 lb/in2 to 2600 ppmmass at 500 °C and 1500 lb/in2[1] |
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Other characteristics | Piezoelectric, may be triboluminescent, chiral (hence optically active if not racemic) |
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References | [2][3][4][5] |
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