metamorphic
Blue Quartz (Aventurine)
Silicon Dioxide (SiO2) with Crocidolite or Magnesio-riebeckite inclusions
Hardness: 7 (Mohs scale); Color: Pale to deep blue, often grainy; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.67
- Hardness
- 7 (Mohs scale)
- Color
- Pale to deep blue, often grainy
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale to deep blue, often grainy; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.67
Formation & geological history
Formed through regional metamorphism where quartz-rich sedimentary rocks (sandstone) are subjected to high heat and pressure, causing recrystallization. The blue color is typically caused by fibrous inclusions of blue minerals like crocidolite.
Uses & applications
Primarily used for ornamental purposes, including beads for jewelry (as seen here), cabochons, decorative carvings, and as a 'healing crystal' in metaphysical practices.
Geological facts
Unlike Lapis Lazuli or Sodalite, Blue Quartz is a macrocrystalline quartz variety. Much of the 'Blue Quartz' in the bead market is actually 'Blue Aventurine,' which owes its color and slight shimmer (aventurescence) to Dumortierite or copper-silicate inclusions.
Field identification & locations
Identify by its hardness (will scratch glass), lack of distinct cleavage, and grainy/speckled blue appearance. It is commonly found in Brazil, India, South Africa, and Russia. Collectors look for evenness of color and high translucency.
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