metamorphic
Quartz / Quartzite
Silicon Dioxide (SiO2)
Hardness: 7 on the Mohs scale. Color: White to grey with translucent patches. Luster: Vitreous to greasy. Crystal structure: Hexagonal/Trigonal system. Cleavage: Poor/indistinct (conchoidal fracture). Specific Gravity: ~2.65.
- Hardness
- 7 on the Mohs scale
- Color
- White to grey with translucent patches
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale. Color: White to grey with translucent patches. Luster: Vitreous to greasy. Crystal structure: Hexagonal/Trigonal system. Cleavage: Poor/indistinct (conchoidal fracture). Specific Gravity: ~2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, the sand grains recrystallize and fuse together into a dense, crystalline rock. The geological age varies wildly based on regional tectonic events.
Uses & applications
Used primarily in construction as crushed stone for road base or railway ballast. Also used in glass making, as an abrasive, and high-quality specimens are used in architectural stone (countertops) or as landscaping rocks.
Geological facts
Quartz is the second most abundant mineral in the Earth's continental crust. Pure quartzite is usually white or gray, but it often occurs in various shades of pink and red due to varying amounts of iron oxide (hematite).
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife (hardness test) and its sugary, crystalline texture. It is found globally in mountainous regions where ancient sedimentary basins have been uplifted and compressed.
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