metamorphic
Quartzite
Metamorphic Quartz (SiO2)
Hardness: 7 on the Mohs scale. Color: reddish-pink to greyish-white. Luster: vitreous to sugary/dull when unpolished. Crystal system: Trigonal (microcrystalline aggregate). Cleavage: None, exhibits conchoidal or uneven fracture. Specific Gravity: 2.65.
- Hardness
- 7 on the Mohs scale
- Color
- reddish-pink to greyish-white
- Luster
- vitreous to sugary/dull when unpolished
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 the Mohs scale. Color: reddish-pink to greyish-white. Luster: vitreous to sugary/dull when unpolished. Crystal system: Trigonal (microcrystalline aggregate). Cleavage: None, exhibits conchoidal or uneven fracture. Specific Gravity: 2.65.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone under extreme heat and pressure. The original quartz grains recrystallize into a interlocking mosaic of quartz crystals. Pink or red tones often arise from trace iron oxide inclusions.
Uses & applications
Used as crushed stone in construction, railway ballast, decorative landscaping gravel, lapidary projects (tumbling/carving), and as a raw material for silica glass production.
Geological facts
Because quartzite is so durable and resistant to chemical weathering, quartzite pebbles often survive long-distance transport in rivers and along beaches, retaining smooth rounded shapes.
Field identification & locations
Identify by its high hardness (scratches glass easily and cannot be scratched by a steel blade) and interlocking sugary quartz texture. Widely found in glaciated riverbeds, mountain gravels, and ancient cratons globally.
More like this
