Physical and chemical characteristics of biogenous silica

Estimation of the silica balance in the ocean requires clarification of the trend of dissolution of biogenous silica. We used biogenous silica in our experiments to compare silica gel and opal. From the results, convenient methods can be devised to estimate the easily soluble parts of biogenous silica. The soluble parts of diatomaceous silica vary considerably with the different species and the characteristics of organic body matter. X-ray diffraction patterns of the biogenous silica suggests an amorphous silica gel form. All different kinds of diatomaceous silica used show infra-red spectra patterns similar to that of silica gel. In the dissolution trends, there exist differences between recent and ancient silica frustules, the former resembling silica gel, the latter opaline silica. Silicious sponge spicules show characteristics similar to that of opaline silica in respect to dissolution and infra-red spectrum pattern. It would, therefore, be reasonable to conclude that there are many forms of biogenous silica ranging from silica gel to pseudo-opaline silica.