Margarite is a calcium rich member of the mica group of the phyllosilicates with formula: CaAl2(Al2Si2)O10(OH)2. It forms white to pinkish or yellowish gray masses or thin laminae. It crystallizes in the monoclinic crystal system. It typically has a specific gravity of aroun 3 and a Mohs hardness of 4. It is translucent with perfect 010 cleavage and exhibits crystal twinning.