Definition of roscoelite in US English:

roscoelite

noun

Mineralogy
  • A vanadium-containing mineral of the mica group, occurring as minute greenish or brownish scales.

Origin

Late 19th century. From the name of Sir Henry Roscoe, English chemist + -lite.

Pronunciation

roscoelite

/ˈrɒskə(ʊ)lʌɪt/