metamorphic
River Pebble (Quartzite/Sandstone mix)
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Tan to light pinkish-brown; Luster: Dull to waxy; Texture: Fine-grained, smooth, and rounded due to water erosion; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Tan to light pinkish-brown
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to light pinkish-brown; Luster: Dull to waxy; Texture: Fine-grained, smooth, and rounded due to water erosion; Cleavage: None (conchoidal fracture).
Formation & geological history
Originates from sandstone that has undergone high heat and pressure (metamorphism). The smooth, ovoid shape is formed through long-term saltation and abrasion in a riverbed or coastal environment.
Uses & applications
Commonly used in landscaping, as decorative gravel, in construction as an aggregate, or as a pocket stone for collectors.
Geological facts
Quartzite is one of the most durable rocks on the Earth's surface. While it starts as sand, the individual grains fuse so tightly that the rock will break through the grains rather than around them.
Field identification & locations
Identify by its hardness (will scratch glass) and its smooth, water-worn texture. Commonly found in current or ancient riverbeds and along beaches.
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