cummingtonite

 
Pronunciation: /ˈkʌmɪŋtənʌɪt/

noun

[mass noun]
  • a mineral occurring typically as brownish fibrous crystals in some metamorphic rocks. It is a magnesium-rich iron silicate of the amphibole group.

Origin:

early 19th century: named after Cummington, a town in Massachusetts, US, + -ite1