mineral

Dumortierite (or Blue Dumortierite Quartz / Variscite)

Dumortierite - Al7BO3(SiO4)3O3

AI-generated identification · may be incorrect

Hardness: 7 to 8.5 on the Mohs scale; Color: denim blue to violet-blue with fibrous or mottled patterning and darker veining; Luster: vitreous to silky or dull; Crystal system: Orthorhombic (typically fibrous or massive aggregates); Specific Gravity: 3.26 - 3.41.

Hardness: 7 to 8
Luster: vitreous to silky or dull

Identified October 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms in high-temperature, aluminum-rich regional metamorphic environments, as well as boron-rich pegmatites and hydrothermally altered rocks.

Uses & applications

Commonly carved into decorative items (such as eggs, spheres, and figurines), cut into cabochons for jewelry, and used in high-grade ceramics due to its high aluminum content.

Geological facts

First described in 1881 in the Rhône-Alpes region of France, it was named in honor of the French paleontologist Eugène Dumortier. It is sometimes mistaken for lapis lazuli or sodalite, but it lacks lapis's pyrite inclusions and calcite banding and is significantly harder.

Field identification & locations

Found widely in Brazil, Madagascar, the United States (Nevada and California), Mozambique, and France. Field identification relies on its distinctive deep denim-blue color, notable hardness (resists scratching by quartz or glass), and dense fibrous texture.