metamorphic
Quartzite (with Metamorphic Foliation)
Quartzite (Recrystallized SiO2)
Hardness: 7 (Mohs scale), Color: Grayish-brown with white quartz veins, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture)
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Physical properties
Hardness: 7 (Mohs scale), Color: Grayish-brown with white quartz veins, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, often during mountain-building events. This specimen shows river-worn smoothing over a long geological period.
Uses & applications
Used in construction as crushed stone, for road ballast, and in the manufacturing of glass and ceramics due to high silica content.
Geological facts
Quartzite is so durable that it often survives intense weathering that destroys surrounding rocks, frequently forming the caps of hills and ridges.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its grainy, sandpaper-like texture that has been fused into a solid mass. Commonly found in riverbeds or glacial deposits.
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