metamorphic
Quartzite Pebble
Metamorphosed Sandstone (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, beige, translucent yellow; Luster: Vitreous to waxy (when river-worn); Crystal structure: Trigeminal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Tan, beige, translucent yellow
- Luster
- Vitreous to waxy (when river-worn)
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, beige, translucent yellow; Luster: Vitreous to waxy (when river-worn); Crystal structure: Trigeminal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed when quartz-rich sandstone is subjected to intense heat and pressure (metamorphism). These specific specimens have been subsequently weathered and rounded by water transport in a river or beach environment.
Uses & applications
Used in construction as crushed stone, in glassmaking if pure, and as decorative river stones for landscaping or craft projects.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock during erosion, which is why it is frequently found as rounded pebbles in streambeds miles from its source.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and lack of visible grains compared to sandstone. These pebbles have a signature 'frosted' or sugary surface texture caused by water tumbling.
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