mineral
Blue Dumortierite in Quartz
Al7(BO3)(SiO4)3O3 (Dumortierite)
Hardness: 7 (in quartz), 7-8.5 (pure mineral); Color: Dark blue, violet-blue, or indigo; Luster: Vitreous to dull; Crystal structure: Orthorhombic; Specific Gravity: 3.26–3.41
- Hardness
- 7 (in quartz), 7-8
- Color
- Dark blue, violet-blue, or indigo
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (in quartz), 7-8.5 (pure mineral); Color: Dark blue, violet-blue, or indigo; Luster: Vitreous to dull; Crystal structure: Orthorhombic; Specific Gravity: 3.26–3.41
Formation & geological history
Formed in aluminum-rich regional metamorphic rocks, as well as in contact metamorphic rocks and boron-rich pegmatites.
Uses & applications
Used in the manufacture of high-grade porcelain, spark plugs, and ceramics due to its high resistance to heat; also used as a gemstone and for lapidary items like tumbled stones and carvings.
Geological facts
It was first described in 1881 for an occurrence in Chaponost, France, and named after the French paleontologist Eugène Dumortier. It is often mistaken for sodalite or lapis lazuli due to its deep blue color.
Field identification & locations
Identify by its distinct fibrous to massive habits and deep blue color that is often mottled within a translucent quartz matrix. Commonly found in Madagascar, Brazil, and the USA (Nevada).
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Mineral
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