metamorphic
Quartzite (River Stone)
Quartzite (predominantly SiO2)
Hardness: 7 (Mohs scale), Color: Pale yellow to tan with white banding, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)
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Physical properties
Hardness: 7 (Mohs scale), Color: Pale yellow to tan with white banding, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. This specimen shows water-worn rounding, indicating transport in a fluvial or glacial environment.
Uses & applications
Used as decorative landscaping stone, in construction as crushed stone, and sometimes as a minor gemstone when polished.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of ridges and mountains. It is more durable than its parent rock, sandstone.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in riverbeds and glacial tills globally.
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