metamorphic
Quartzite Pebble
Metamorphosed Sandstone (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, beige, or yellowish-brown; Luster: Vitreous to waxy; Texture: Granular but smooth due to water erosion; Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs scale)
- Color
- Tan, beige, or yellowish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, beige, or yellowish-brown; Luster: Vitreous to waxy; Texture: Granular but smooth due to water erosion; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together. This specific specimen has been smoothed by fluvial or coastal transport over thousands of years.
Uses & applications
Used as decorative stone in landscaping, aquarium gravel, or as a source of high-purity silica for the glass and metallurgical industries.
Geological facts
Quartzite is so tough that when it breaks, it fractures through the quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in riverbeds or beaches where softer rocks have eroded away, leaving only the durable quartzite behind.
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