metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, beige, or brownish due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, beige, or brownish due to iron oxide impurities
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, beige, or brownish due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, quartz grains recrystallize and fuse together into a dense, hard rock. This specimen appears weathered and rounded by water or glacial transport.
Uses & applications
Commonly used as a decorative stone in landscaping, as road ballast, and in the production of glass or silica-based industrial products. Polished stones are sometimes used in jewelry or as pocket stones.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the jagged peaks of mountain ranges. It is harder than the sandstone it originates from and will break through the quartz grains rather than around them.
Field identification & locations
Identify in the field by its extreme hardness (it will scratch glass easily) and its grainy, sugary texture. It is ubiquitous in glaciated regions and riverbeds across North America and Europe.
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