metamorphic
Blue Quartzite
Quartzite with inclusions (often Dumortierite or Magnesio-riebeckite)
Hardness: 7 (Mohs scale); Color: Grayish-blue to deep blue; Luster: Vitreous to dull; Crystal structure: Trigonal (granular/massive); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 to 2.7
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-blue to deep blue
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-blue to deep blue; Luster: Vitreous to dull; Crystal structure: Trigonal (granular/massive); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 to 2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Specifically, its blue hue is caused by the inclusion of blue minerals during the recrystallization process under high heat and pressure.
Uses & applications
Used primarily in lapidary work for cabochons and beads, as well as decorative landscaping stones and occasional countertops or tiles in construction.
Geological facts
Unlike Lapis Lazuli or Sodalite, blue quartzite is much harder and will easily scratch glass. The blue color is often unevenly distributed, appearing as streaks or dense patches within a white or gray quartz matrix.
Field identification & locations
Identify by its extreme hardness (7) and granular sugary texture when viewed closely. While found globally, significant deposits of blue quartzite are frequently sourced from Brazil and the United States.
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