metamorphic
Blue Quartzite
Quartzite with inclusions (often Dumortierite or Magnesio-riebeckite), SiO2
Hardness: 7 (Mohs scale); Color: Pale to medium blue with greyish tones; Luster: Vitreous to waxy; Structure: Crystalline/Granular; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 - 2.7
- Hardness
- 7 (Mohs scale)
- Color
- Pale to medium blue with greyish tones
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale to medium blue with greyish tones; Luster: Vitreous to waxy; Structure: Crystalline/Granular; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 - 2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Under intense heat and pressure, original quartz grains recrystallize and fuse together. The blue color is typically caused by the inclusion of blue fibrous minerals during the metamorphic process.
Uses & applications
Used primarily as decorative stone, in landscaping, for countertops, and as a semi-precious stone for lapidary work and tumbled stones.
Geological facts
Quartzite is so durable that it often outlasts the surrounding softer rocks, forming ridges and hilltops. Blue quartzite is specifically prized by collectors for its rare coloration, which is not common in pure quartz rocks.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its grainy, 'sugar-like' texture on fresh breaks. Found commonly in Brazil, India, and parts of the Appalachian Mountains in the USA.
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