metamorphic
Quartzite
Metamorphic Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to reddish-brown (likely due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.63 - 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Tan to reddish-brown (likely due to iron oxide staining)
- 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: Tan to reddish-brown (likely due to iron oxide staining); Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.63 - 2.65.
Formation & geological history
Formed from the metamorphism of quartz sandstone under high tectonic pressure and temperature. The individual quartz grains recrystallize and fuse together, creating an extremely hard and durable rock.
Uses & applications
Used as a decorative stone in construction, crushed stone for road ballast, and sometimes as a source of silica for glass manufacturing. Dense varieties are used for kitchen countertops and floor tiles.
Geological facts
Quartzite is so hard that it will scratch glass and steel. It is more resistant to weathering than the sandstone from which it originated, often forming ridges or resistant peaks in mountainous regions.
Field identification & locations
Identify by its interlocking crystalline texture and hardness (it cannot be scratched by a knife). Commonly found in folded mountain belts. Use a scratch test against glass to confirm presence of high silica content.
More like this
