An example of an inorganic mineral is calcite. Having a trigonal system, it appears pearly with a vitreous or glass-like lustre. Calcite, a common mineral, can be found in colors such as red, yellow and white.
Two of calcite's prominent features are its low Mohs hardness, which is 3, and distinguished cleavage. Having a chemical formula of CACO3, calcite often shows a fluorescent quality. This means it lights up under X-ray, cathode ray or ultraviolet light. Calcite reacts strongly with acids, even weak ones, such as vinegar. It can be found in sedimentary rocks, especially limestone, marble, peridotites and kimberlites.