What is "steacyite"

n. (context mineralogy English) A tetragonal-ditetragonal dipyramidal mineral containing calcium, manganese, oxygen, potassium, silicon, sodium, and thorium.

Steacyite is a complex silicate mineral containing thorium and uranium; formula K( Ca, Na)( Th, U) Si O. It forms small brown or yellow green crystals, often cruciform twinned crystals. It is radioactive. It was discovered at Mont-Saint-Hilaire, Quebec in 1982 and is named after Harold Robert Steacy (1923–2012), mineralogist.