metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale. Color: White to light grey with rusty orange-brown iron oxide staining along fractures. Luster: Vitreous to sugary (granoblastic). Cleavage: None (conchoidal to uneven fracture). Specific Gravity: 2.63 - 2.65.
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to sugary (granoblastic)
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Physical properties
Hardness: 7 on Mohs scale. Color: White to light grey with rusty orange-brown iron oxide staining along fractures. Luster: Vitreous to sugary (granoblastic). Cleavage: None (conchoidal to uneven fracture). Specific Gravity: 2.63 - 2.65.
Formation & geological history
Formed when quartz-rich sandstone undergoes intense heat and pressure during regional or contact metamorphism, causing individual quartz grains to recrystallize and interlock tightly.
Uses & applications
Used extensively in construction as crushed stone, road ballast, dimension stone, counter tops, decorative landscaping, and historically as building stone.
Geological facts
Unlike sandstone which breaks around its sand grains, quartzite is so strongly recrystallized that it breaks directly through the constituent quartz grains when fractured.
Field identification & locations
Field identification involves testing hardness (scratches glass easily) and looking for a sugary crystalline texture where fractures cut directly through grains rather than around them. Found globally in mountainous metamorphic terrains.
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