Dumortierite is a fibrous variably colored aluminium boro mineral, Al7BO3(SiO4)3O3. Dumortierite crystallizes in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals and vary in color from brown to more rare violet and other tri-valent elements for aluminium result in the color variations. It has a Mohs hardness of 7 and a specific gravity from red to blue to violet. Dumortierite quartz is blue colored quartz containing abundant dumortierite inclusions.
Dumortierite was first described in 1881 for an occurrence in Chaponost and named for the French paleontologist Eugène Dumortier It typically occurs in high temperature aluminium rich regional metamorphic rocks, those resulting from contact metamorphism. The most extensive investigation on dumortierite was done on samples from the high grade metamorphic Gfohl unit by Fuchs et al. (2005).
It is used in the manufacture of high grade porcelain. It is sometimes mistaken for sodalite and has been used as imitation lapis lazuli.
Sources of Dumortierite include Austria , Canada, Namibia , Poland.