metamorphic
Quartzite Pebble
Quartzite (SiO2)
Mohs hardness: 7. Color: Tan, brownish-orange, pinkish-gray, and cream. Luster: Vitreous to dull/waxy. Texture: Fine-grained, sugary (granoblastic), stream-rounded pebble. Specific Gravity: 2.65.
- Hardness
- 7
- Color
- Tan, brownish-orange, pinkish-gray, and cream
- Luster
- Vitreous to dull/waxy
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Physical properties
Mohs hardness: 7. Color: Tan, brownish-orange, pinkish-gray, and cream. Luster: Vitreous to dull/waxy. Texture: Fine-grained, sugary (granoblastic), stream-rounded pebble. Specific Gravity: 2.65.
Formation & geological history
Formed from the regional or contact metamorphism of quartz sandstone. High heat and pressure cause quartz grains to recrystallize, fusing them tightly together. This stream-worn pebble was subsequently eroded and rounded by water transport.
Uses & applications
Commonly used as construction aggregate, railway ballast, decorative landscaping gravel, and for lapidary tumbling.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering. Unlike sandstone, which breaks around quartz grains, quartzite breaks through the grains when fractured due to its fused crystalline structure.
Field identification & locations
Identified by its sugary granular texture, extreme hardness (scratches glass easily), smooth stream-rounded shape, and lack of reaction to acid. Abundant in riverbeds, glacial deposits, and gravel pits worldwide.
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