metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale. Color: Pale yellow to tan. Luster: Vitreous to waxy. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Pale yellow to tan
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: Pale yellow to tan. Luster: Vitreous to waxy. Crystal structure: Hexagonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic belts. This specific specimen has been further shaped into a smooth pebble by water erosion in a stream or river bed.
Uses & applications
Used primarily in construction (crushed stone), as ball mill media, and as decorative river stones in landscaping or aquarium decor.
Geological facts
Quartzite is so tough that it usually breaks through the quartz grains rather than along their boundaries. It is one of the most durable rocks on Earth's surface.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its sugary, crystalline texture under a lens. It is ubiquitous in riverbeds and glacial deposits globally.
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