A new interfacial method for conodont separation

Abstract

Conodonts display higher specific gravity (2.84-3.10) than common minerals in sedimentary rocks. For several decades this property has been exploited to separate these microfossils from sediment residues using density separation techniques. Two heavy liquids commonly used, bromoform and tetra-bromoethane, are toxic (Sax, 1979; HaufTand Airey, 1980) and constitute a danger to human health. Tetrabromoethane is a known carcinogen (Brem et al., 1974). Both of these liquids should be abandoned in favor of nontoxic sodium polytungstate (Callahan, 1987; Merrill, 1987b; Krukowski, 1988). There are, however, some technical problems with its use because of relatively high viscosity and a tendency to recrystallize during separation. Another big disadvantage is also its price at $100 per kilogram. These problems may be considerably overcome by using polytungstate in the way described by Savage (1988).