The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having close to 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.

The word "mica" is derived from the Latin word mica, meaning "a crumb", and probably influenced by micare, "to glitter".

Read more about Mica:  Mica Classification, Occurrence and Production, Properties and Uses, Substitutes, Mica in Ancient Times, Mica Powder