metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, brownish, or gray; Luster: Dull to vitreous; Structure: Granoblastic, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, brownish, or gray
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brownish, or gray; Luster: Dull to vitreous; Structure: Granoblastic, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, often during mountain-building events (orogeny). This specific piece has been rounded by fluvial or glacial transport.
Uses & applications
Used as track ballast for railroads, in construction as decorative stone or gravel, and occasionally for primitive tools in prehistoric times.
Geological facts
Quartzite is so durable that it often survives through multiple cycles of erosion, outlasting the original mountains from which it came.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary appearance despite being a dense rock. Commonly found in riverbeds, glacial tills, and ancient mountain belts.
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