A trioctahedral member of the brittle mica group. The end-member formula is: CaLiAl2(BeAlSi2)O10(OH)2. Compositional range restriction includes viLi > vi□, where □ = vacancy (i.e., viLi < vi□ is defined as margarite). Bityite forms in the 2M1 polytype and has been found in pegmatites from Madagascar, Zimbabwe, and the Urals, and in a tin vein in Uganda. Like margarite, bityite (Lin and Guggenheim, 1983) has nearly complete tetrahedral ordering of Al,Be vs Si, and thus is non-centric in symmetry (Cc space group).
Cf., margarite