Definition of niocalite in US English:

niocalite

noun

Mineralogy
  • A basic orthorhombic silicate and fluoride of niobium and calcium, (Ca,Nb)₄Si(O,OH,F)₉, which occurs as yellow crystals.

Origin

1950s. From nio- + cal- + -ite; apparently coined by E. H. Nickel.

Pronunciation

niocalite

/ˌnʌɪəʊˈkalʌɪt/