**4. Biomineralogy**

Izatulina et al. [7] studied the effect of bacteria that are present in human urine on the crystallization of oxalate and phosphate mineral phases, the most common constituents of renal stones. It was shown that the inflammatory process will contribute to the decrease in oxalate supersaturation in urine due to calcium oxalate crystallization, while the change in urine pH and the products of bacterial metabolism will be of major importance in the case of phosphate mineralization.

Rusakov et al. [8] reported on the mechanisms of Sr-to-Ca substitution in the structures of calcium oxalate minerals that were found in lichen thalli on Sr-bearing apatite rock. It was shown that the incorporation of Sr ions is less preferable than Ca into the structures of whewellite and weddellite, and substitution rates are slightly higher for weddellite than for whewellite, which is most likely caused by the denser manner of the interpolyhedral linkage in the latter structure.

Five Cacteae species were studied using various experimental techniques to characterize the biomineral composition within their different tissues by De la Rosa-Tilapa et al. [9]. Calcium carbonates and silicate phases were detected along with common calcium oxalates.
