Monazite

Cerium-lanthananum-didymium phosphate, usually with thorium oxide and silica; it also sometimes contains yttrium and erbium earths. The mountain regions of w. N. C. have recently yielded it in the form of sand or rolled grains in river beds; it is also found in Brazil. The mineral is used in manufacturing mantles for the Welsbach incandescent gas-burners.