metamorphic
Quartzite cobblestone
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Pinkish-orange (due to iron oxide staining); Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-orange (due to iron oxide staining)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-orange (due to iron oxide staining); Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).
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 rounded and smoothed by fluvial or glacial transport.
Uses & applications
Quartzite is used heavily in construction as decorative stone, railway ballast, and in the production of glass and industrial silica products.
Geological facts
Quartzite is so hard that it will scratch glass. It is often more resistant than the surrounding rocks, which is why it often caps mountains and ridges.
Field identification & locations
Identify by its extreme hardness and grainy sugar-like texture under a hand lens. It can be found in riverbeds, glacial tills, and mountainous regions worldwide.
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