metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or pink; Luster: vitreous to dull; Crystal structure: Trigonal (microscopic grains); Cleavage: none, breaks with conchoidal fracture; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or pink
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or pink; Luster: vitreous to dull; Crystal structure: Trigonal (microscopic grains); Cleavage: none, breaks with conchoidal fracture; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, where quartz grains recrystallize into an interlocking mosaic. Found in orogenic belts and tectonic plate boundaries.
Uses & applications
Used in construction as crushed stone or dimension stone, in the manufacture of glass and ceramics, and as a decorative stone in jewelry or landscaping.
Geological facts
Quartzite is so hard and chemically resistant that it often forms prominent ridges and hills in landscapes because it erodes much slower than surrounding rocks.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its sugary, granular appearance that doesn't fizz with acid. Common in mountainous regions like the Appalachians or the Alps.
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