The Bureau of Mines conducted laboratory studies on Idaho mudstones to examine techniques for extracting vanadium. Recovery of vanadium from low-grade sources could contribute to future vanadium production and reduce reliance on imports. An Idaho mudstone surface sample containing 0.30 pct v2o5 and an underground sample containing 0.21 pct v205 were used in the extraction tests. Leaching of the surface sample for 18 h at 80 deg c with the addition of up to 1,000 lb/ton h2so4 recovered 70 pct of the vanadium. However, leaching of the underground sample under the same conditions recovered only 47 pct. By adding 15 wt pct nacl and roasting the samples at 750 deg c for 2 h, followed by leaching with 800 lb/ton h2so4, vanadium extractions were increased to 78 pct from the surface sample and 83 pct from the underground sample. Water leaching of samples roasted at 750 deg c for 4 h with a 25-wt-pct nacl addition yielded about 60 pct of the vanadium from both surface and underground samples. Autoclave leaching at 200 deg c for 3 h with 1,000 lb/ton h2so4 extracted 97 pct of the vanadium from the surface sample and 86 pct from the underground sample. An exploratory solvent extraction investigation to purify and concentrate vanadium in the leach solution using several organic reagents was also conducted.