Shape Development and Structure of a Complex (Otoconia-Like ?) Calcite-Gelatine Composite

摘要

A large number of recent publications deal with control of the size and shape of calcium carbonate in its calcite modification by organic additives acting as growth modifiers or templates. Other reports focus not only on shape control but also on the control of the calcium carbonate modification formed. Only a few publications concentrate on calcite specimens showing a habit that is more or less close to the shape of biogenic (calcite) otoconia (see Figure 1), charac-terized by their barrel-shaped habit with triplanar faceted ends. These include spindle-shaped, rhombohedrally truncated specimens obtained in the presence of malonic acid, the development of additional (sometimes even structured) faces extending nearly parallel to the c-axis direction in the presence of γ-carboxyglutamate or α-aminosuccinate, malic acid together with urea, glycoproteins extracted from sea-urchin spines, and nacre proteins.