mineral

Dumortierite Quartz

Al7BO3(SiO4)3O3 (inclusion in SiO2)

Hardness: 7 (Quartz) to 8.5 (Dumortierite); Color: Blue, violet-blue, or grayish-blue with needle-like inclusions; Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific Gravity: 2.65 - 3.41

Hardness: 7 (Quartz) to 8
Luster: Vitreous to dull

Identified June 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed in aluminum-rich regional metamorphic rocks and occasionally in granitic pegmatites. The blue color is provided by Dumortierite inclusions within a Quartz matrix.

Uses & applications

Primarily used for high-quality porcelain, spark plugs, and laboratory equipment due to its high alumina content. Also popular as a gemstone for jewelry and ornamental 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 but is significantly harder.

Field identification & locations

Identify by its distinctive fibrous or needle-like blue inclusions. It is found in Brazil, Sri Lanka, Madagascar, and the USA (California/Nevada). Collectors look for deep indigo color and clarity of the surrounding quartz.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic