Rapid methods of analyzing soils and stream sediments for readily extracted ore metals have been widely used in mineral exploration. The methods in most common use involve the simultaneous treatment of the sample with 2 immiscible liquids, one a cold aqueous extractant, and the other a solution of dithizone in toluene or hexane. Dithizone is a colorimetric indicator reagent that reacts quantitatively with Cu, Pb, and Zn. These procedures determine only a small fraction, normally about 5%, of the total metal content of strictly residual soils. Where the metal in the soil or sediment is not residual but has originated by precipitation from metal-rich natural waters, the fraction extracted may be substantially higher than 5%. Procedures for the dithizone field tests are described in detail, the chemical reactions are explained, and some common operational problems are discussed.

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