metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: White, gray, or yellowish; Luster: Vitreous to dull; Crystal structure: Trigonal (as quartz grains); Cleavage: None, breaks with conchoidal fracture; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- White, gray, or yellowish
- Luster
- Vitreous to dull
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: White, gray, or yellowish; Luster: Vitreous to dull; Crystal structure: Trigonal (as quartz grains); Cleavage: None, breaks with conchoidal fracture; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used as crushed stone for road construction and railway ballast; polished slabs are used for countertops, flooring, and decorative stone cladding.
Geological facts
Quartzite is so hard that it can scratch steel easily. It is one of the most durable rocks on Earth's surface and often forms the caps of mountain ranges because it resists erosion better than surrounding rocks.
Field identification & locations
Identify in the field by its extreme hardness and the fact that it breaks through quartz grains rather than around them (unlike sandstone). Commonly found in folded mountain belts globally.
More like this
