In comparison to the other precious stones and precious metals corals are not minerals, they have got an organic origin. They are coelenterates which emit calcium carbonate and this forms a skeleton, the coral. The chemical formula is CaCO3. The hardness is about 2.5 to 3. Corals are white or red. Because of their organic origin some conditions must be fulfiled that corals can grow. It is important that the water is warm. The Mediterranean and tropic areas are good for corals. To have enough coelenterates the water has to be warm. Corals are fragile
and they have got a rough surface, but they change, when they are polished. When we compare raw and processed corals they
are not similar to each other. In the antiquity there were made jewels of corals, too.
Data about Corals
Chemical formula
CaCO3
Mineral class
carbonates
Crystal system
skeleton of coelenterates
Hardness
2,5 to 3
Density
2.6 g/cm3
Color
white, rose, red, grey
Line color
white
Gloss
glass gloss
Break
shell
Fissileness
none
Author and Webmaster: Lukas Czarnecki
If you have got questions about corals you can send me an e-mail under the following adress:
webmaster@hpwt.de
