Amethyst
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Amethyst | |
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![]() Amethyst cluster frae Magaliesburg, Sooth Africae. | |
General | |
Category | Mineral variety |
Formula (repeatin unit) | Silica (silicon dioxide, SiO2) |
Creestal seestem | rhombohedral class 32 |
Identification | |
Colour | Purpie, violet |
Creestal habit | 6-sided prism endin in 6-sidit pyramid (typical) |
Twinnin | Dauphine law, Brazil law, an Japan law |
Cleavage | None |
Fractur | Conchoidal |
Mohs scale haurdness | 7–lawer in impure varieties |
Skinkle | Vitreous/glossy |
Streak | White |
Diaphaneity | Transparent tae translucent |
Speceefic gravity | 2.65 constant; variable in impur varieties |
Optical properties | Uniaxial (+) |
Refractive index |
nω = 1.543–1.553 nε = 1.552–1.554 |
Birefringence | +0.009 (B-G interval) |
Pleochroism | None |
Meltin pynt | 1650±75 °C |
Solubility | insoluble in common solvents |
Ither chairacteristics | Piezoelectric |
Amethyst is a violet variety o quartz eften uised in jewelry. The name comes frae the Auncient Greek ἀ a- ("nae") an μέθυστος methustos ("intoxicatit"), a reference tae the belief that the stane pertectit its ainer frae drunkenness. The auncient Greeks an Romans wore amethyst an made drinkin vessels o it in the belief that it wad prevent intoxication. It is ane o several furms o quartz. Amethyst is a semiprecious stane an is the tradeetional birthstane for Februar.