metamorphic
Quartzite
Quartzite (principally SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, often with tan or yellowish staining; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Specific gravity: approx 2.65.
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray, often with tan or yellowish staining; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Specific gravity: approx 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events.
Uses & applications
Used extensively in road construction aggregate, as a decorative stone in landscaping, and sometimes in glass manufacturing if pure enough.
Geological facts
Quartzite is one of the most durable rocks found on the Earth's surface and often forms high ridges because it resists weathering better than surrounding rocks.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel nail) and its tendency to break across sand grains rather than around them; commonly found in mountainous or glaciated regions.
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