metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to light pinkish-brown; Luster: Vitreous to waxy when polished; Crystal structure: Trigonal/Hexagonal system (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.8.
- Hardness
- 7 on Mohs scale
- Color
- Tan to light pinkish-brown
- Luster
- Vitreous to waxy when polished
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to light pinkish-brown; Luster: Vitreous to waxy when polished; Crystal structure: Trigonal/Hexagonal system (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.8.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped and smoothed by fluvial or alluvial erosion processes (river tumbling), likely occurring over millions of years.
Uses & applications
Used primarily as decorative landscaping stone, in road construction as crushed stone, and occasionally for high-durability countertops. Small tumbled pebbles are popular in lapidary work and as pocket stones.
Geological facts
Quartzite is so durable that it can withstand chemical weathering better than almost any other rock. On mountaintops, quartzite often forms the resistant 'cap' that prevents the peak from eroding away.
Field identification & locations
Identify in the field by its ability to scratch glass and its sugary texture under a hand lens. It lacks the graininess of sandstone because the quartz grains have recrystallized and fused together. Commonly found in riverbeds and glacial deposits.
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