metamorphic
Quartzite River Stone
Quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: Tan, grey, and creamy white swirls. Luster: Dull to vitreous when wet or polished. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None, conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- Tan, grey, and creamy white swirls
- Luster
- Dull to vitreous when wet or polished
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Physical properties
Hardness: 7 on Mohs scale. Color: Tan, grey, and creamy white swirls. Luster: Dull to vitreous when wet or polished. Crystal Structure: Hexagonal (microcrystalline). Cleavage: None, conchoidal fracture.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial erosion in a river or stream.
Uses & applications
Used as decorative landscaping stone, in construction aggregates, and occasionally as a source of silica for industrial processes.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock, which is why it is frequently found as rounded boulders or pebbles in riverbeds and on beaches long after the parent rock has eroded.
Field identification & locations
Look for a stone that cannot be scratched by a steel knife and lacks the visible sand grains of its parent sandstone. Common in glacial till and river deposits globally.
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