metamorphic
Quartzite
Quartzite (mostly SiO2)
AI-generated identification · may be incorrectHardness: ~7; Color: reddish-brown; Luster: vitreous to dull; Crystal structure: granular, massive; Cleavage: none; Specific gravity: ~2.65
- Hardness
- ~7
- Color
- reddish-brown
- Luster
- vitreous to dull
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Physical properties
Hardness: ~7; Color: reddish-brown; Luster: vitreous to dull; Crystal structure: granular, massive; Cleavage: none; Specific gravity: ~2.65
Formation & geological history
Formed from quartz-rich sandstone altered by heat, pressure, and chemical activity. The reddish-brown color is typically due to iron oxide impurities (hematite).
Uses & applications
Used for decorative stone, crushed stone for road construction, railway ballast, and occasionally as a source of silica. When tumbled or polished, used by collectors or for decorative purposes.
Geological facts
Quartzite is very hard and resistant to weathering, often forming ridges or hilltops. The specimen shown appears to be smoothed, either naturally by water action or artificially tumbled.
Field identification & locations
Can be identified by its hardness (scratches glass), granular texture, and lack of cleavage. Found worldwide in areas of regional metamorphism.
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