hjelmite
noun
hjelm·ite
variants or less commonly hielmite
ˈ(h)yelˌmīt,
hēˈel-
plural -s
: a black mineral that contains yttrium, iron, manganese, uranium, calcium, columbium, tantalum, tin, and tungsten oxide, is often metamict, and has uncertain affinities compare samarskite, tapiolite
Word History
Etymology
Swedish hjelmit, from P. J. Hjelm †1813 Swedish chemist + Swedish -it -ite