- © The Mineralogical Society Of America
The primordial earth surface exposed minerals comprised mainly of carbonates, silicates and smaller amounts of phosphates. Weathering eventually led to the dissolution of the surface rock and the leaching of their components into the rivers, lakes and oceans. There, complex chemistry depending upon the temperature, pH, pressure, and atmospheric carbon dioxide content led to the reprecipitation of the dissolved minerals into new forms as part of the sedimentary rock. The minerals themselves could be transformed by passive diagenesis to further structures. When primitive organisms emerged, they added a very significant component to the processing of the dissolved mineral constituents in the marine environment, where both prokaryotic and eukaryotic organisms have the ability to produce mineralized skeletal elements and mineralized fecal pellets that also accumulate in the marine sediments. The increasing diversity of plant and animal life has continually accelerated the dynamic relationship between the composition of the earths crust and the living world. The resulting minerals of biogenic origin comprise a surprisingly large portion of the earths crust, and represent a huge reservoir of sequestered carbonate, silicate and phosphate ions. The majority of the carbonates appear as calcite or aragonite, produced principally by plankton, invertebrates and so on, while the phosphates, as carbonated hydroxyapatite, are the products of vertebrates as well as the weathering of igneous rock.
This chapter is focused on the mechanisms of formation of the vertebrate mineralized structures; bone, tooth enamel, tooth dentin and otoliths. Although other Chapters deal explicitly with the invertebrate and bacterial systems, we need to consider if there are any general considerations that apply to all biogenic mineralization systems. We shall begin from that perspective and inquire as to the way by which living organisms can organize their mineral phases into such complex and specific structures.
BIOMINERALIZATION: GENERAL ASPECTS
The term “Biomineralization” implies that a mineral …