10Be in bauxite and commercial aluminum

Abstract Five different samples of commercial aluminum have 10 Be concentrations that range from a low of 40 × 10 6 to a high of 100 × 10 6 (atom 10 Be)/(g Al). The beryllium-10 is probably produced in the atmosphere and introduced into aluminum ore deposits in varying amounts by rainwater during ore genesis. One modern ore, a bauxite from Haiti, contains ~ 6 × 10 9 atom 10 Be/(g sample) or 5.7 × 10 10 atom 10 Be/(g Al). Geologically older, allocthonous bauxite from Arkansas contains considerably less 10 Be; this observation suggests that 10 Be can be used to constrain the age of the deposit. The presence of 10 Be in commercial aluminum makes it inadvisable to add modern Al to small samples in which very low levels of 10 Be are to be determined.