metamorphic
Quartzite River Pebble
Metamorphosed sandstone (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Grayish-tan to white; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None; Specific gravity: 2.6 - 2.8
- Hardness
- 7 on Mohs scale
- Color
- Grayish-tan to white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-tan to white; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None; Specific gravity: 2.6 - 2.8
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure, typically during regional metamorphism related to tectonic plate collisions. This specific specimen has been rounded and smoothed by water transport in a river or coastal environment.
Uses & applications
Used as construction aggregate, decorative landscaping stone, and in glass manufacturing if pure enough. Water-worn pebbles are often used in interior design and aquariums.
Geological facts
Quartzite is one of the most physically durable and chemically resistant rocks found at the Earth's surface. It is so tough it will typically break through the quartz grains rather than around them.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel blade) and its grainy, sandpaper-like texture beneath a smooth surface. Found globally in riverbeds and mountainous regions.
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