1. Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity.
2. A diamond formed naturally in the Earth is a mineral. A synthetic diamond made in a laboratory is not a mineral. Inorganic: These substances are not made from living things, nor from the remains of living things. Coal is not a mineral because it is composed of the remains of ancient plants.
3. A mineralogist is a person who studies minerals.
4. Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3). It often has variable amounts of silica in it, as well as varying amounts of clay, silt, and sand. Limestone rocks fall under the category of sedimentary rocks that are made from mineral calcite.