Dumortierite
Dumortierite belongs to the silicate group. It contains aluminium, iron, boron and silicon. Its chemical formula is Al7BO3 ( SiO4 ) 3O3 .
Dumortierite typically occurs in massive forms, but can also develop radiating crystal clusters. Its color ranges from red to blue, and greenish specimens are also found. Dumortierite has a high hardness, greater than 7/10 on the Mohs scale (10 for diamond), and an average density of 3.3 (1 for water). The streak on porcelain is white.
DUMORTIERITE owes its name to the French paleontologist Eugène Dumortier.
