Gibbsite occurs in soils and saprolites derived from feldspathic biotite and hornblend gneiss and layered amphibolite in Chambers County, Alabama. This region lies in a humid, subtropical climatic zone in the Piedmont physiographic province of east-central Alabama. Three target areas (I, II, and III) were selected on the basis of reconnaissance sampling carried out during the first phase of the study. Soil and saprolite samples were collected at 5-ft (1.52-M) intervals from shallow auger drill holes in the target areas. Gibbsite content of samples, as measured by differential scanning calorimeter (dsc), range from zero to 72 pct. Areas containing more than the average 10 pct gibbsite (dsc) are outlined for each target area and estimates of gibbsite tonnages were made for each. The gibbsite-rich saprolite blanket is usually within the first 20 ft (6.1 M) of the surface in the b and upper part of the c soil horizons. Gibbsite concentrations are richer where the depth of weathering is not more than 25 ft (7.62 M) because unweathered bedrock is conducive to internal drainage depending upon the mineralogy and orientation of rock structure. Estimated tonnage of 10 pct (dsc) or more gibbsite for target area I is 554,880 metric tons, target area II is 50,616 metric tons, and target area III is 309,729 tons.