A silicate mineral, hydrous aluminum borosilicate
(Al8BSi3O19[OH]). It is found scattered
in metamorphic rocks, and occurs usually
in fibrous masses, rarely as orthorhombic crystals. Dumortierite is glassy
to pearly violet or blue. Hardness 7; relative density 3.3.
|A sample of dumortierite from Madagascar
AND PLANETARY SCIENCE