Structure of Muscovite

Minerals

• Minerals are solid crystalline substances that occur naturally in the Earth’s crust. Muscovite belongs to a class of minerals called silicates, which make up 90 percent of the Earth’s surface.

Chemistry

• Minerals have orderly internal structures. The way the atoms of a molecule of muscovite align and the forces that hold it together form the crystal structure.

Features

• Minerals exist in geometric shapes. Muscovite forms t-o-t sandwiches—two layers of tetrahedrons with an octahedron layer sandwiched in between. Each t-o-t sandwich is connected to another by van der Waal bonds, which are very weak.

Cleavage

• Muscovite and other micas break along their van der Wall bonds, forming thin sheets. Cleavage describes the surface along which a mineral breaks naturally. Muscovite has one major cleavage due to its sheet-like structure.

Function

• “Muscovy glass,” which was composed of several layers of muscovite, was used for window panes before the discovery of glass. Today, micas are valuable for growing crops and in construction materials.