metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, but can be pink or red; Luster: vitreous to dull; Crystal structure: granular, non-foliated; Cleavage: none; Specific gravity: approx. 2.65.
- Hardness
- 7 on Mohs scale
- Color
- typically white to gray, but can be pink or red
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray, but can be pink or red; Luster: vitreous to dull; Crystal structure: granular, non-foliated; Cleavage: none; Specific gravity: approx. 2.65.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. Geological age varies by location, often millions of years old.
Uses & applications
Extensively used in construction as crushed stone for road grit and railroad ballast, in glass manufacturing, and as decorative dimension stone for countertops and flooring.
Geological facts
Quartzite is so hard and durable that it often forms the crests of mountain ranges because it resists weathering better than surrounding rocks. It is harder than steel.
Field identification & locations
Identify in the field by its grainy, sandpaper-like texture that lacks a gritty feel because the grains are fused. It will scratch glass easily. Commonly found in folded mountain belts globally.
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