dumortierite

 
Pronunciation: /djʊˈmɔːtɪərʌɪt/

noun

[mass noun]
  • a rare blue or violet mineral occurring typically as needles and fibrous masses in gneiss and schist. It consists of an aluminium and iron borosilicate.

Origin:

late 19th century: from the name of V.-E. Dumortier (1802–76), French geologist, + -ite1