Wiktionary
avogadrite
n. (context mineral English) An orthorhombic-dipyramidal mineral containing boron, cesium, fluorine, and potassium.
Wikipedia
Avogadrite
Avogadrite ((K,Cs)BF) is a potassium- caesium tetrafluoroborate in the halide class.. Avogadrite crystallizes in the orthorhombic system ( space group Pnma) with cell parameters a 8.66 Å, b 5.48 Å and c Å 7.03.