Bauxite is a mineral with a dull, earthy luster which is usually white or gray, though sometimes can be found stained by yellow, orange, red, pink, or brown by iron or included iron minerals. It has no cleavage, a low specific gravity, and the Mohs Hardness Scale score is between 1 and 3. Its streak is usually white, but its iron stain can discolor. It has a variable chemical composition but is always rich in aluminum oxides and hydroxides. These are most of the identifying properties for bauxite and are useful for identifying the mineral; however, bauxite is most often processed into another material with properties much different than bauxite.Bauxite is primarily a metallic mineral though it is also used as an industrial mineral. It is the only ore used for large scale aluminium production. Although aluminium is the most abundant metallic element in the earth’s crust constituting about 8%, it usually occurs in clays, soil and rocks that cannot be utilized for its extraction.Mullite is the mineralogical name for the only chemically stable intermediate phase in the SiO2–Al2O3 system. The mineral rarely occurs in its natural form and can be found on the Isle of Mull off the western coast of Scotland.Flint clays are highly variable in color, have a distinctive milky luster, and a conchoidal fracture. Flint clay is a variety of clay-rich rock in which the clay mineral is predominantly kaolinite.Kaolin is a type of clay found in nature. It can also be made in a laboratory. People use it to make medicine.