The minerals can be found in living things in three ways:
Precipitated mineral salts
Precipitated mineral salts constitute solid, insoluble structures with skeletal function. For instance:
- Calcium carbonate in the shells of mollusks , crustaceans , corals and vertebrates .
- Calcium phosphate, Ca3 (PO4 )2, which, together with calcium carbonate, which, deposited on collagen , constitute bones .
- Silica (SiO2 ) in the exoskeletons of diatoms and grasses, etc.
Dissolved mineral salts
The dissolved mineral salts are dissociated into ions:
- Cations: Na+ , K+, Ca2+ and Mg2+.
- Anions: Cl- , SO42- , PO42- , HCO3- , CO32- and NO3-.