metamorphic
Quartzite
Quartzite (Primary mineral: SiO2)
Hardness: 7 on Mohs scale; Color: Pinkish-tan/gray; Luster: Vitreous to dull; Crystal Structure: Non-foliated, interlocking quartz grains; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-tan/gray
- 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 on Mohs scale; Color: Pinkish-tan/gray; Luster: Vitreous to dull; Crystal Structure: Non-foliated, interlocking quartz grains; Cleavage: None (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 the sand grains to recrystallize and fuse together. The pinkish tint often indicates trace amounts of iron oxide (hematite).
Uses & applications
Commonly used in construction as road ballast, roofing granules, and as a decorative stone in landscaping. High-purity quartzite is used in the glass and metallurgy industries.
Geological facts
Quartzite is so hard that when it breaks, it fractures through the individual sand grains rather than around them, which distinguishes it from sandstone. It is extremely resistant to chemical weathering.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid. Commonly found in folded mountain belts and ancient shield areas like the Appalachians or the Canadian Shield.
More like this
