Biotite is a silicate mineral and belongs to the mica class of minerals. It is composed of dark-colored layered silicate minerals containing iron, magnesium, and aluminum. The name biotite is derived from the Greek word "biotos" meaning "muscle" and refers to its common occurrence in muscovite mica. Biotite is also called "biotite" or "side mica" because of its deep color.

Biotite is commonly found in medium- to coarse-grained igneous and metamorphic rocks such as gneiss, schist, and granite. It is also found in sedimentary rocks such as shale and limestone. Biotite is usually found in flakes or flakes and ranges in color from black to dark brown.

The most striking physical characteristic of biotite is its hexagonal crystal structure. Biotite has basal cleavage, which means it can split easily along crystal planes. Its cleavage planes are at 60 degree angles to each other, forming a hexagon. This hexagonal crystal structure is what distinguishes biotite from muscovite.

Muscovite is another type of mica mineral. It is a silicate mineral composed of potassium, aluminum and hydroxide ions. The name muscovite is derived from the Latin "muscovite," meaning "Moscow mica," referring to its common occurrence in the Moscow region of Russia. Muscovite is also known as "muscovite" due to its light-colored appearance.

Muscovite is commonly found in medium- to coarse-grained igneous and metamorphic rocks, such as gneiss and schist. It is also found in sedimentary rocks such as shale and limestone. Muscovite is usually in the form of flakes or flakes and is white to light gray in color.

The most striking physical characteristic of muscovite is its monoclinic crystal structure. Muscovite has cleavage planes, which means it can easily split into two parts at a 90 degree angle. Its cleavage planes are at an angle of 90 degree to each other, forming a monoclinic crystal system. This monoclinic crystal structure is what distinguishes muscovite from biotite.