metamorphic
Quartzite
Metamorphic Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: White to grayish-white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- White to grayish-white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to grayish-white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. This specimen appears to be water-worn, likely found in a riverbed or coastal environment.
Uses & applications
Used in construction as crushed stone, in glass manufacturing, and as a decorative stone in landscaping. High-purity quartzite is a source of silica.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, frequently forming hills and ridges. It is often confused with marble but will scratch glass while marble will not.
Field identification & locations
Identify by its hardness (it scratches glass) and grainy texture that looks like sandpaper but feels smooth to the touch if water-worn. Found worldwide in mountain ranges and near river systems.
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