English Name：Black Coral
Chemical Composition：Conchiolin (Mainly from horny organic)
Crystal System：Amorphous, Organic Material
Hardness：2.5 - 3.5
SG：1.3 - 2.2
Locality：West Indies, off the Hawaiian Islands, Australia and in Southern water towards Antarctica
Remarks：Coral is secreted by animals called coral polyps.
Coral is the supporting structure for the body of the polyp, which lives in a rigid skeleton or 'cup'.
Some colonial corals build structures known as reefs, which are the accumulated supporting structures of successive generations of polyps.