metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or pinkish; Luster: vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: none, exhibits conchoidal or irregular fracture; Specific gravity: approx. 2.65.
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or pinkish
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or pinkish; Luster: vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: none, exhibits conchoidal or irregular fracture; Specific gravity: approx. 2.65.
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. Intense heat and pressure cause the quartz grains to recrystallize and fuse together. It can date back to various geological eras, including the Precambrian.
Uses & applications
Used widely in construction for railway ballast, floor tiles, and countertop surfaces. Also used as a decorative stone in architecture and landscaping.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the crests of ridges and mountains because it resists erosion much better than surrounding rocks. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify in the field by its sugary texture on fresh surfaces and its extreme hardness (it will not be scratched by a steel knife). Look for it in mountainous regions or areas with exposed metamorphic bedrock.
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