Definition of ramsdellite in US English:

ramsdellite

noun

Mineralogy
  • A manganese-containing mineral that occurs as grey to black, platy, or finely crystalline masses, and is dimorphous with pyrolusite.

Origin

1940s. From the name of Lewis S. Ramsdell, U.S. mineralogist, who described the mineral in 1932 ( Amer. Mineral 17 143–9) + -ite.

Pronunciation

ramsdellite

/ˈramzdəlʌɪt/