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RESEARCH PRODUCT

Discovery of Ca oxalate crystals associated with fungi in moss travertines (Bryoherms, freshwater heterogeneous stromatolites)

subject

description

Buffered decalcification of live moss and liverwort (Hepaticae) travertines resulted in the release of a large number of organisms (bacteria, cyanobacteria, fungi, eukaryotic algae, and small animals), which constitute an “organic mat”; (also called an algal mat or biofilm). This mat is calcified and commonly has laminations, allowing moss travertines to be considered as stromatolitic structures. After decalcification of 300 samples of travertines (using dilute acetic acid), only 9 released Ca oxalate crystals in the form of needle bundles, spherulites, and tetragonal bipyramidal prisms. These crystalline forms are identical to those found in some phanerophytes and soils. Mycelian filaments also exist in travertines mostly composed of algae, and it is possible that Ca oxalate crystals can be formed. However, being metastable, these crystals transform very quickly into calcite by diagenesis, in the same way as aragonite in the stromatolites of saltwater environments.