Amethyst
| Amethyst | |
|---|---|
Amethyst cluster frae Magaliesburg, Sooth Africae.
|
|
| General | |
| Category | Mineral variety |
| Formula (repeating unit) |
Silica (silicon dioxide, SiO2) |
| Identification | |
| Color | Purpie, violet |
| Crystal habit | 6-sided prism endin in 6-sidit pyramid (typical) |
| Crystal seestem | rhombohedral class 32 |
| Twinnin | Dauphine law, Brazil law, an Japan law |
| Cleavage | None |
| Fractur | Conchoidal |
| Mohs scale hairdness | 7–lawer in impure varieties |
| Luster | Vitreous/glossy |
| Streak | White |
| Diaphaneity | Transparent tae translucent |
| Specific 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 characteristics | 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 would prevent intoxication. It is ane o several furms o quartz. Amethyst is a semiprecious stane an is the tradeetional birthstane for Februar.
