Biomineral
A biomineral is a mineral that is produced by a living organism. The term usually refers to inorganic materials such as bones, teeth, and shells, but it can also include some organic materials such as coral. Biominerals are often very hard and resistant to erosion, making them valuable resources for humans. Some of the most well-known biominerals include calcium carbonate (limestone), silica (quartz), and apatite (bone phosphate).