A NEW METHOD FOR THE EXTRACTION OF MACROFOSSILS FROM CALCAREOUS ROCKS USING SULPHURIC ACID

Abstract:  A new method for the extraction of calcified and/or partly pyritized macrofossils has been developed. This method is based upon the differential speeds for the dissolving of microcrystalline and macrocrystalline calcite in 38% sulphuric acid. The effectiveness of the sulphuric acid treatment is also influenced by the volume of clay minerals in the host rock. Therefore, this method is highly applicable for the extraction of macrofossils from marlstones, marly limestones, and other lithified calcareous sediments. The main advantages of this method, when compared with other chemical methods, are (1) the short treatment time, (2) the capability of dissolving the sediment on the fossil's surface, and (3) its efficiency in dissolving calcareous rocks with low porosity. This method has been successfully applied to Upper Cretaceous macrofossils from the Bohemian Cretaceous Basin. The surface of extracted macrofossils remained undamaged, exhibiting minute skeletal details; perhaps even encrusters and bioerosions.