Definition of cummingtonite in English:

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Pronunciation: /ˈkəmiNGtəˌnīt/


A mineral occurring typically as brownish fibrous crystals in some metamorphic rocks. It is a magnesium-rich iron silicate of the amphibole group.
Example sentences
  • Accessory chlorite, magnetite or ilmenite, titanite, apatite, partly chloritized biotite, epidote, pyrite and sometimes cummingtonite, are present.
  • This rock is a dark gray schistose rock containing radiating aggregates of cummingtonite and occasionally pyrrhotite.
  • The two minerals can have similar distinctive brown colors and are hard to differentiate from each other, although cummingtonite is typically darker and slightly denser.


Early 19th century: named after Cummington, a town in Massachusetts, + -ite1.

For editors and proofreaders

Syllabification: cum·ming·ton·ite

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