metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale. Color: White, grey, reddish-brown. Luster: Vitreous to dull. Crystal structure: Trigonal (microcrystalline). Cleavage: None. Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- White, grey, reddish-brown
- 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, grey, reddish-brown. Luster: Vitreous to dull. Crystal structure: Trigonal (microcrystalline). 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 quartz grains to recrystallize and fuse together, typically in orogenic belts during mountain-building events.
Uses & applications
Used in construction as crushed stone for road ballast, as a decorative dimension stone in countertops and floor tiles, and historically as a source for silica in glassmaking.
Geological facts
Quartzite is so tough that it often outlasts other rocks; it can be found as rounded river pebbles or cobbles long after the parent rock has eroded. It is significantly harder and more durable than the sandstone from which it originated.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and its grainy, sugary texture. Unlike sandstone, quartzite fractures through the quartz grains rather than around them. Found globally where ancient mountain ranges existed.
More like this
