The oysters are nucleated with a bead composed of mother-of-pearl and a small piece of mantle tissue. This bead becomes the nucleus of the pearl and is the reason akoya pearls are more often perfectly round.
Carbon definition, Chemistry. a widely distributed element that forms organic compounds in combination with hydrogen, oxygen, etc., and that occurs in a pure state as diamond and graphite, and in an impure state as charcoal.
Carbon is a chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalentâmaking four electrons available to form covalent chemical bonds.t occurs in several different natural structures, eg diamond and graphite. Diamond occurs when the carbon atoms are packed together in the most compact form, with the central carbon atom connected to four others, each at a 107.something degree angle to each other.