Coral
CaC03

The oldest known findings of red coral date from the Mesopotamian civilization from about 3000 BC. For centuries, this was the coral par excellence, and at the time of Pliny Elder it was much appreciated in India, even more than in Europe. Coral comes from the Calcarious skeletons of colonies of marine organisms. The skeletons vary in color: from bright to dark red, slightly orange-red, pink, and white. The most highly prized varieties of coral are those that are uniform, strong, bright red. It has a hardness of 2.5 - 4 on the Moh's scale. Coral occurs in the Mediterranean Ocean, along the coast of China, Vietnam, and Japan. The red coral from the Mediterranean has very faint concentric rings. It is easier to see the longitudinal structures.