metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan with yellow staining from iron; Luster: vitreous to dull; Crystal structure: trigonal (microcrystalline); Cleavage: none; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan with yellow staining from iron
- 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: typically white, gray, or tan with yellow staining from iron; Luster: vitreous to dull; Crystal structure: trigonal (microcrystalline); Cleavage: none; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional or contact 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, railroad ballast, and as a raw material in the glass and ceramics industries. High-purity quartzite is used to produce ferrosilicon and silicon metal.
Geological facts
Quartzite is so tough that it often survives intense weathering better than the rocks surrounding it, leading to the formation of prominent ridges and peaks in mountain ranges.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel blade) and sugary, granular appearance. Unlike sandstone, it breaks across grains rather than around them. Commonly found in folded mountain belts.
More like this
