mineral
Quartz (Smoky/Milky Variety)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Gray, brown, to white; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Gray, brown, to white
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Gray, brown, to white; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the crystallization of silica-rich magma or from hydrothermal veins. Smoky varieties often gain color from natural irradiation of aluminum impurities over millions of years.
Uses & applications
Used in glass manufacturing, electronics (piezoelectric properties), abrasives, and as semi-precious gemstones in jewelry and decor.
Geological facts
Quartz is one of the most abundant minerals in Earth's crust. Smoky quartz is the national gem of Scotland, where it is known as Cairngorm.
Field identification & locations
Identify by its hardness (scratches glass), lack of cleavage, and waxy-to-glassy luster. Commonly found in granitic pegmatites and metamorphic rocks wordwide.
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metamorphic
Gypsum (variety Selenite or Alabaster)
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Mineral
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Mineral/Rock
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