Organisms from all five phylogenetic kingdoms form minerals. No less than 60 different mineral types are known, to date, to be formed by organisms and these are located at a wide variety of tissue sites and fulfill a host of different functions (Lowenstam and Weiner, 1989). A prominent and well known function of biogenic minerals is to provide mechanical strength to skeletons and often at the same time to act as a reservoir for the supply of ions necessary for vital metabolic functions. A characteristic of the mineral component of most skeletons is that it is formed under unusually well controlled conditions, such that the mineral form bears no morphological resemblance to its inorganic counterpart. This is, for the most part, achieved by inducing the minerals to precipitate in preformed spaces located by complex assemblies of macromolecules or vesicles or in some cases by combinations of both.