metamorphic
Quartz / Quartzite
Quartz (Silicon Dioxide, SiO2)
Hardness: 7 (Mohs scale); Color: White to off-white/translucent; Luster: Vitreous (glassy) to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- White to off-white/translucent
- Luster
- Vitreous (glassy) to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: White to off-white/translucent; Luster: Vitreous (glassy) to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, or as massive hydrothermal vein quartz. Found in diverse geological environments ranging from Precambrian to more recent eras.
Uses & applications
Used in glass making, as an abrasive, in construction as aggregate, and in high-precision electronics (piezoelectric). Translucent varieties are used in lapidary work and beads.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. It is chemically very resistant at the Earth's surface, which is why it often remains as pebbles long after other minerals have weathered away.
Field identification & locations
Identify in the field by its inability to be scratched by a steel blade, lack of cleavage, and translucent 'milky' appearance. Commonly found in riverbeds, glacial deposits, and mountain ranges globally.
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