A new method for extracting conodonts and radiolarians from chert with NaOH solution

Microfossils are important components of sedi-mentary rocks used for palaeontological, biostratigraphic,palaeoenvironmental and palaeoclimatic investigations. Theyare usually extracted from rocks using an acid solution, whichmight vary depending on the embedding rock lithology. Herewe propose a new method using common NaOH (sodiumhydroxide; soda) to digest cherts (micro- and cryptocrystallinequartz) instead of the standard technique based on HF(hydrofluoric acid). This new method allows the collection ofundamaged specimens of different kinds of microfossils, suchas conodonts, radiolarians, teeth and dermal scales, the miner-ology of which is still preserved (e.g. biogenic apatite in cono-donts). The use of soda is thus recommended, as it is lessdangerous, less expensive, and it better preserves the extractedmicrofossils both in shape and mineralogy.Key words:chert, soda, conodont, radiolarian, chemicalmethod, dissolution technique