metamorphic
Quartzite Pebble
Quartzite (composed primarily of Silica, SiO2)
Hardness: 7 on Mohs scale; Color: Tan to yellowish-brown; Luster: Dull to vitreous; Crystal structure: Trigonal (microcrystalline); Texture: Granular; Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan to yellowish-brown
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to yellowish-brown; Luster: Dull to vitreous; Crystal structure: Trigonal (microcrystalline); Texture: Granular; Specific Gravity: 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under high heat and pressure, typically during mountain-building events. This specific specimen has been further shaped into a rounded pebble by water erosion in a river or coastal environment.
Uses & applications
Used in construction as crushed stone, in glass manufacturing if highly pure, as a decorative garden stone, and as a durable abrasive material.
Geological facts
Quartzite is so tough that it often survives intense weathering that destroys other rocks, leading it to form prominent ridges and peaks. It is often confused with marble, but quartzite is much harder and will not react with acid.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife (unlike limestone or marble) and its sugary, granular texture. Commonly found in riverbeds, glacial deposits, and ancient mountain belts.
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