mineral

Dumortierite Quartz (Blue Quartz)

Al7(BO3)(SiO4)3O3 / Quarz with Dumortierite inclusions

Hardness: 7 (Mohs scale), Color: Denim blue to violet-blue, Luster: Vitreous to waxy, Crystal structure: Trigonal/Orthorhombic inclusions, Cleavage: Poor to none, Specific gravity: 2.65 - 3.41

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Denim blue to violet-blue, Luster: Vitreous to waxy, Crystal structure: Trigonal/Orthorhombic inclusions, Cleavage: Poor to none, Specific gravity: 2.65 - 3.41

Formation & geological history

Formed in regional metamorphic rocks rich in aluminum, as well as in pegmatites and hydrothermally altered volcanic rocks. The blue color comes from dumortierite inclusions within the quartz matrix.

Uses & applications

Used primarily as a decorative stone, in jewelry (cabs and beads), as a gemstone for collectors, and in the production of high-grade ceramics and porcelain due to its high-heat resistance.

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 but lacks the white calcite or metallic pyrite inclusions typical of those stones.

Field identification & locations

Identify by its distinct denim-blue color and hardness (it can scratch glass). Commonly found in Brazil, Namibia, Madagascar, and the United States (Nevada). For collectors, look for deep, uniform blue color and high translucency.

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