The mica group of minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic with a tendency towards pseudo-hexagonal crystals and are similar in chemical composition. The highly 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 thought to be derived from the Latin word micare, meaning to shine, in reference to the brilliant appearance of this mineral (especially when in small scales).
Specific varieties of mica include: