metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (as constituent grains); Cleavage: none; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white to light gray
- Luster
- vitreous to dull
Identified More metamorphic →
Explore Quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (as constituent grains); Cleavage: none; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used in construction as road ballast, for building stone, roofing tiles, and as a source of silica for glass making and industrial abrasives.
Geological facts
Quartzite is so hard that it will scratch steel. It is one of the most resistant rocks to chemical and physical weathering, often forming the peaks of mountain ranges.
Field identification & locations
Identify by its ability to scratch glass and its granular, sugary appearance. Unlike marble, it will not fizz when exposed to dilute acid. Common in metamorphic mountain belts worldwide.
