metamorphic
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
Hardness: 7 on Mohs scale. Color: Orangey-pink to light brown/tan due to iron oxide inclusions. Luster: Vitreous to waxy. Structure: Granoblastic/massive. Cleavage: None, exhibits conchoidal or uneven fracture. Specific Gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Color
- Orangey-pink to light brown/tan due to iron oxide inclusions
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: Orangey-pink to light brown/tan due to iron oxide inclusions. Luster: Vitreous to waxy. Structure: Granoblastic/massive. Cleavage: None, exhibits conchoidal or uneven fracture. Specific Gravity: ~2.65.
Formation & geological history
Formed when quartz-rich sandstone or chert is subjected to high heat and pressure during regional metamorphism, recrystallizing the quartz grains into an interlocking mosaic.
Uses & applications
Used as crushed stone in construction, railway ballast, decorative landscaping gravel, building stone, and occasionally tumbled for gemstone collections.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering. When struck, it breaks across the constituent quartz grains rather than along their boundaries, unlike its parent rock sandstone.
Field identification & locations
Identify in the field by its high hardness (scratches glass easily) and sugary to fused quartz texture. Widely found in mountain ranges, ancient shield areas, and river gravel deposits worldwide.
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