![Blue Quartz (Dumortierite Quartz) (SiO2 containing inclusions of Dumortierite [Al7(BO3)(SiO4)3O3]) — metamorphic](https://media.rock.id/blue-quartz-dumortierite-quartz-ac9f36db-c1ae-4257-b360-cfa07a07e993-compressed.jpg)
metamorphic
Blue Quartz (Dumortierite Quartz)
SiO2 containing inclusions of Dumortierite [Al7(BO3)(SiO4)3O3]
Hardness: 7 Mohs; Color: Denim blue to violet-blue mottled with white; Luster: Vitreous to dull; Crystal structure: Hexagonal (Trigonal); Cleavage: None; Specific Gravity: 2.65-2.70
- Hardness
- 7 Mohs
- Color
- Denim blue to violet-blue mottled with white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 Mohs; Color: Denim blue to violet-blue mottled with white; Luster: Vitreous to dull; Crystal structure: Hexagonal (Trigonal); Cleavage: None; Specific Gravity: 2.65-2.70
Formation & geological history
Formed through the regional metamorphism of silica-rich rocks where aluminum and boron were present, leading to the growth of fibrous dumortierite inclusions within the quartz matrix. Most specimens are from the Precambrian to Paleozoic eras.
Uses & applications
Primarily used for ornamental carvings, jewelry (cabochons and beads), and as a collector's mineral specimen. It is also used in metaphysical practices.
Geological facts
Unlike sapphire or lapis lazuli, the blue color in this rock comes from microscopic mineral inclusions rather than trace elements in the crystal lattice. It is often mistaken for Sodalite, but quartz is significantly harder.
Field identification & locations
Commonly found in Brazil, South Africa, and Madagascar. In the field, look for a blue-flecked, grainy appearance and test the hardness; it will easily scratch glass, distinguishing it from softer blue minerals like calcite or sodalite.
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