DISCOVERY OF CA OXALATE CRYSTALS ASSOCIATED WITH FUNGI IN MOSS TRAVERTINES (BRYOHERMS, FRESH-WATER HETEROGENEOUS STROMATOLITES)

Buffered decalcification of live moss and liverwort (Hepaticae) traver tines resulted in tire release of a large number of organisms (bacteri a, cyanobacteria, fungi, eukaryotic algae, and small animals), which c onstitute an ''organic mat'' (also called an algal mat or biofilm). Th is mat is calcified and commonly has laminations, allowing moss traver tines to be considered as stromatolitic structures. After decalcificat ion of 300 samples of travertines (using dilute acetic acid), only 9 r eleased Ca oxalate crystals in the form of needle bundles, spherulites , and tetragonal bipyramidal prisms. These crystalline farms are ident ical to those found in some phanerophytes and soils. Mycelian filament s also exist in travertines mostly composed of algae, and it is possib le that Ca oxalate crystals carl 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 environmen ts.