Bacterial leaching tests were performed on chat pile rock from the picher field in northeastern Oklahoma and on slime pond sediment from the creta mine in southwestern Oklahoma. Using t. Ferrooxidans in shake flasks at 26 deg c, 38 pct of the zinc in the chat pile rock could be leached in 15 days, while complete leaching of zinc was achieved in 5 days with s. Acidocaldarius at 70 deg c in shake flasks. The copper in creta mine sediment could be completely leached in 24 h with t. Ferrooxidans at 26 deg c in shake flasks. In a stirred fermentor with 3 l of liquid, the copper could be completely leached in 12 h at an airflow rate of 0.1 Vol/vol/min. A preliminary design and economic analysis of scaling up the fermentation gave a cost of $5.74/Lb copper extracted, based on processing 17,400 lb of sediment per day. The economics could possibly be greatly improved by substantially increasing the weight of sediment processed per run; this would require experimental verification.