metamorphic
Quartzite Pebble (River Rock)
Quartzite (mainly SiO2)
Hardness: 7 on Mohs scale. Color: Tan, yellowish-brown, or light gray due to iron staining. Luster: Vitreous to waxy. Structure: Granular, non-foliated. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Tan, yellowish-brown, or light gray due to iron staining
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: Tan, yellowish-brown, or light gray due to iron staining. Luster: Vitreous to waxy. Structure: Granular, non-foliated. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. It has subsequently been eroded and polished over thousands of years by water action in a river or coastal environment.
Uses & applications
Used in landscaping, construction as crushed stone, as a source for silica in glassmaking, and frequently collected as 'worry stones' or for rock tumbling.
Geological facts
Quartzite is so hard and chemically resistant that it often survives intense weathering better than other rocks. It is harder than steel; a steel knife will usually leave a metallic streak on the stone rather than scratching it.
Field identification & locations
Identify it by its extreme hardness (will scratch glass) and its smooth, water-worn texture. Commonly found in riverbeds, glacial deposits, and beaches. It lacks the layered look of sedimentary sandstone.
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