Dumortierite

Dumortierite is a mineral from the borosilicate group, primarily composed of aluminum borosilicate (Al₇BO₃(SiO₄)₃O₃).

It is distinguished by its shades of blue, bluish-violet, pink, or brown, often in the form of fibrous or massive aggregates. It mainly forms in aluminum-rich metamorphic rocks, often associated with quartz, muscovite, and tourmaline, notably in France, Brazil, the United States, and Madagascar.