Mica

Mica is a mineral name given to a group of minerals that are physically and chemically similar.  They are all silicate minerals, known as sheet silicates because they form in distinct layers.  Micas are fairly light and relatively soft, and the sheets and flakes of mica are flexible. Mica is heat-resistant and does not conduct electricity.  There are 37 different mica minerals. The most common include: purple lepidolite, black biotite, brown phlogopite and clear muscovite.