Mica

Mica (ˈmī-kə )-XY_2-3Z₄O₁₀(OH)₂

As you can tell from the formula (with all those variables) Mica will have an abundance of varieties. They are a large group of sheet silicates that can be parted into flexible brittle sheets.

Two different subdivisions are recognized for Mica. The first being True Micas, or Common Micas (Muscovite, Paragonite, or Ephesite), or the Brittle Micas(Margarite or Clintonite). It is also subdivided into Dioctahedral Mica (Muscovite or Paragonite) and Trioctahedral (Biotite or Lepidolite).