Each semester at the University of Arkansas, students in General Geology courses are required to learn to identify a number of common minerals and rocks by their physical properties. Now, for the first time, examples of the mineral and rock specimens are being made available as digital images on the World-Wide Web.
Biotite is a type of mica, a family of sheet silicates.
Muscovite is a type of mica, a family of sheet silicates. Halite is the only mineral eaten by humans. Gypsum is the main component in plaster and wall board. Calcite is a very common mineral and the main mineral in limestone. It really is magnetic.