Bityite is defined as a brittle mica since calcium cations assume the position in the interlayer instead of potassium. Beryllium replaces some of the silicon cations in the Tetrahedral positions and lithium takes on the positions in the octahedral positions between the layers. One of a handful of lithium micas and the only one with essential beryllium.
Bityite usually occurs as thin tabular and pseudohexagonal crystals to 2mm or as rosettes of dense or compact aggregates. Found sparingly in lithium rich pegmatites. (Encycl. of Min.). Weak yellow Fl.
This is a nice specimen with countless small 1-2mm white platy crystals on Biotite matrix. The Bityite exhibits weak yellow FL.