This research addresses the occurrence, speciation, and distribution of tungsten in the vicinity of abandoned mines near Bishop, CA. Tungsten, most commonly found as tungstate (WO₄^2-), exists in mineral phases such as sheelite (CaWO₄), ferberite (FeWO₄), and huebernite (MnWO₄). Tungstate can also form adsorption complexes with the siloxane surface groups associated with phyllosilicates and the hydroxyl groups associated with the edges of inorganic minerals such as Fe-oxides and Al-oxides, and kaolinite.

A modified fractionation scheme was used to target specifically bound, sorbed, and mineral phases tungsten. Weakly adsorbed W was extracted by ammonium chloride followed by an ammonium fluoride (NH₄F) solution, which separates Al-W from Fe-W. Fe-W was extracted with NaOH and reductant-soluble W with citrate dithionite bicarbonate (CBD). Calcium-tungstate was extracted with H₂SO₄. Residual tungsten was extracted by a modified microwave acid digest.

The sequential extraction analysis found most of the tungsten in the soil and sediment was in a residual form. Fe-W and reductant-soluble-W represented about 20 % of the total W. XANES data indicate fully oxidized W(VI)-adsorbed complexes. The locations of the samples with the highest W concentrations were found in the active stream channel and stream terraces. The W appears to be transported away from the abandon mine spoils either as residual mineral forms or as W-adsorbed complexes.