<Tr> <Th> Diagnostic features </Th> <Td> cleavage </Td> </Tr> <Tr> <Th> References </Th> <Td> </Td> </Tr> <P> The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having nearly perfect basal cleavage . All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition . The nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet - like arrangement of its atoms . </P> <P> The word mica is derived from the Latin word mica, meaning a crumb, and probably influenced by micare, to glitter . </P>

The cleavage properties of mica result form the-