metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: White to grey; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoiodal/jagged fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- White to grey
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: White to grey; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoiodal/jagged fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone subjected to extreme heat and pressure, causing quartz grains to recrystallize and fuse together. Typically found in mountain belts and Precambrian shields.
Uses & applications
Used as decorative stone in architecture, railway ballast, road construction, glass manufacturing, and as a durable material for countertops. Historically used for stone tools due to its hardness.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, forming ridges and mountain peaks. Unlike sandstone, quartzite breaks through the quartz grains rather than around them.
Field identification & locations
Identify in the field by its grainy, sugary texture and extreme hardness (it will easily scratch glass and stainless steel). It is commonly found in metamorphic terranes worldwide.
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