metamorphic
Quartzite
Quartzite (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale. Color: White, light gray, yellowish to pinkish-tan due to iron oxide impurities. Luster: Vitreous to sugary/sandy on fresh surfaces. Texture: Granoblastic, interlocking quartz grains. Cleavage: None (fractures concavity across grains). Specific gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to sugary/sandy on fresh surfaces
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Physical properties
Hardness: 7 on Mohs scale. Color: White, light gray, yellowish to pinkish-tan due to iron oxide impurities. Luster: Vitreous to sugary/sandy on fresh surfaces. Texture: Granoblastic, interlocking quartz grains. Cleavage: None (fractures concavity across grains). Specific gravity: ~2.65.
Formation & geological history
Formed when quartz-rich sandstone undergoes intense heat and pressure during regional metamorphism, fusing the individual sand grains into a dense, crystalline mass of quartz.
Uses & applications
Used in construction as crushed stone, railway ballast, decorative building stone, countertop slabs, and historically as a raw material for stone tools.
Geological facts
Unlike sandstone which breaks around individual quartz grains, quartzite fractures directly through the quartz grains because the intergranular matrix has been completely recrystallized.
Field identification & locations
Identified in the field by its high hardness (scratches glass easily), sugary crystalline surface, and tendency to break across quartz grains. Commonly found in mountainous regions, ancient cratons, and riverbeds.
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