mineral
Amethyst
Quartz (Silicon Dioxide with iron impurities), SiO2
Hardness: 7 (Mohs scale); Color: Pale violet to deep purple; Luster: Vitreous/Glassy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Pale violet to deep purple
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale violet to deep purple; Luster: Vitreous/Glassy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Forms in hydrothermal veins or inside volcanic geodes (amygdules) when silica-rich water cools. The purple color is caused by trace amounts of iron radiated by surrounding rocks. The region of Hyderabad (17.5°N, 78.3°E) is part of the Deccan Traps and surrounding Precambrian terrain where quartz varieties are common.
Uses & applications
Widely used for semi-precious jewelry, ornamental carvings, and as a popular specimen for mineral collectors. Historically used in amulets and drinking vessels.
Geological facts
The name comes from the Greek word 'amethystos', meaning 'not intoxicated', as it was believed to prevent drunkenness. It is the birthstone for February.
Field identification & locations
Identified by its purple color and hardness (it will scratch glass). In the field, look for hexagonal crystal points or purple masses inside basaltic or granite cavities. While found globally, significant deposits exist in Brazil, Uruguay, and India.
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