Non-marine radiaxial fibrous calcites—examples of speleothems proved by electron backscatter diffraction

The occurrence of radiaxial fibrous calcites (RFC) in speleothems is documented for the first time using the new electron backscatter diffraction (EBSD) method. Up to now, in speleothems these precipitates have only been observed as Mg-containing calcites in close association with aragonite, in caves of the temperate to cool Central European regions with mean annual temperatures between 4 and 16 °C. As the four studied occurrences are located in caves in dolomitic and/or ankeritic host rocks, magnesium is considered to be of particular importance for triggering the formation of radiaxial fibrous (Mg-) calcite.