mineral
Dumortierite Quartz (Blue Quartz)
Al7BO3(SiO4)3O3 with Quartz (SiO2)
Deep denim-blue to royal blue color, vitreous to dull luster, Mohs hardness 7 (quartz matrix), hexagonal crystal system, no cleavage, specific gravity ~3.26-3.41.
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Physical properties
Deep denim-blue to royal blue color, vitreous to dull luster, Mohs hardness 7 (quartz matrix), hexagonal crystal system, no cleavage, specific gravity ~3.26-3.41.
Formation & geological history
Formed in high-temperature aluminum-rich regional metamorphic rocks, pegmatites, and hydrothermally altered rocks.
Uses & applications
Used for ornamental carvings, polished cabochons, beads, decorative gemstones, and in high-grade aluminum ceramics.
Geological facts
First described in 1881 by Eugène Bertrand and named in honor of French paleontologist Eugène Dumortier. It is often mistaken for sodalite or lapis lazuli.
Field identification & locations
Identified by its distinctive denim-blue streak-free appearance, high hardness (scratches glass easily), and lack of calicite or pyrite inclusions compared to lapis lazuli. Commonly found in Brazil, Madagascar, France, and the USA.
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