Rubicline

Rubicline, also referred to as Rb-microcline, is the rubidium analogue of microcline, an important tectosilicate mineral. Its chemical formula is (Rb, K)[AlSi₃O₈] with an ideal composition of RbAlSi₃O₈. Chemical analysis by electron microprobe indicated the average weight of the crystal is 56.66% SiO₂, 16.95% Al₂O₃, and 23.77% Rb₂O, along with trace amounts of caesium oxide (Cs₂O) and iron(III) oxide (Fe₂O₃).