metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-brown with dark banding; Luster: Dull to waxy; Texture: Fine-grained, granular, and smooth due to river tumbling; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Grayish-brown with dark banding
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-brown with dark banding; Luster: Dull to waxy; Texture: Fine-grained, granular, and smooth due to river tumbling; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing quartz grains to recrystallize. This specific specimen has been further shaped by fluvial (river) or glacial erosion.
Uses & applications
Commonly used in construction as aggregate, landscaping, or as decorative river stones. Occasionally used in primitive tool making due to its hardness.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often ending up as rounded pebbles in riverbeds far from its source outcrop.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary appearance under magnification. Commonly found in riverbeds, beaches, and glacial till globally.
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