metamorphic
Blue Quartzite (Blue Aventurine / Dumortierite Quartz)
Quartzite with inclusions (SiO2 with AlAl4BSi3O18)
Hardness: 7 (Mohs scale), Color: Sky blue to deep denim blue, Luster: Vitreous (waxy when polished), Crystal Structure: Trigonal (granular mass), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.8
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Physical properties
Hardness: 7 (Mohs scale), Color: Sky blue to deep denim blue, Luster: Vitreous (waxy when polished), Crystal Structure: Trigonal (granular mass), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. The blue coloration is typically caused by fibrous inclusions of minerals like dumortierite or crocidolite during high-pressure recrystallization.
Uses & applications
Used primarily for decorative purposes, including architectural cladding, countertops, tumbled gemstones for jewelry (beads, cabochons), and as a metaphysical 'healing stone'.
Geological facts
Natural blue quartzite is relatively rare compared to other metamorphic colors. It is often mistaken for Sodalite or Lapis Lazuli, but can be distinguished by its superior hardness and lack of white calcite or gold pyrite inclusions.
Field identification & locations
Identify in the field by its grainy, sugary texture and inability to be scratched by a steel knife. Common locations include Brazil, South Africa, and parts of the United States (California/Virginia). Collectors look for uniform blue saturation and translucent edges.
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