A mineral is a naturally occurring , solid, crystalline substance with a specific chemical composition. Minerals are usually inorganic and are formed by ionic, covalent or metallic bonding. Ionic bonds are the dominant type of bonds in mineral strictures. 90% of all minerals are ionic compounds. Minerals bonded by covalent bonds are strong, for example carbon bonded together to form diamond. Metallic bonds are a type of covalent bonds where the atoms have a strong tendency to lose electrons and pack together as cations.