Ceramic is a solid substance containing organic or iron-containing organ or iron bonded ionic or bonding bonds. Typical examples of clay, mud and clay. Synthetic crystals vary from very soft to crystal-like, are compacted, and are often completely absorbed (e.g. glass). Usually, composite clay vessels are joined or physically bonded as is the case with mud, stone and clay. Variations in the growth of the mold and the formation of electrons in ionic bonding and assembly make many ceramic materials remain warm and electrically active. With a range of unselected selection / composition methods, the size of the subject is large, and the identification features are difficult to determine for the whole group. General features such as high melting temperature, high hardness, high strength, high modulus of elasticity, chemical resistance and low elasticity are common, with no known symptoms.