Calcite forms in many different geologic environments. Usually colorless or white it can occur in many tints due to the inclusion of minor constituents during formation. It has possibly more habits of occurrence than any other mineral.
Chemical composition: Ca[CO3]; Hardness: 3; Trigonal
Hematite is a common iron oxide that is sometimes magnetic. It is iron, grey in color and is found throughout the world near the earth’s surface.
Chemical composition: Fe2O3; Hardness: 5-6