metamorphic
Quartzite Pebble
Metaquartzite
Hardness: 7 on Mohs scale; Color: Tan, brown, and grey; Luster: Dull to waxy; Texture: Granoblastic, fine-grained; Cleavage: None (conchoidal fracture when broken)
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, and grey
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, and grey; Luster: Dull to waxy; Texture: Granoblastic, fine-grained; Cleavage: None (conchoidal fracture when broken)
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Under high heat and pressure, quartz grains recrystallize and fuse into a dense, hard rock. This specimen has been rounded by fluvial (river) or glacial transport.
Uses & applications
Used as a decorative garden stone, railway ballast, aggregate in construction, and as a durable material for stone tools in prehistoric times.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock layers, ending up as rounded pebbles in riverbeds millions of years after its parent formation has eroded away. It is significantly harder than glass.
Field identification & locations
Identify by its hardness (will scratch glass easily) and its ability to break through individual quartz grains rather than around them. Commonly found in riverbeds, glacial tills, and beaches.
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