Calcic plagioclase (An69 Ab30), albite (An6 Ab94), and microcline (An2 Ab31 Or67) were leached over a 10-wk period at 13°C with 10−4M solutions of a number of low-molecular-weight organic acids. The effectiveness of the organic acids in dissolving the feldspars was found to be citric ≈ oxalic > salicylic > protocatechuic ≈ gallic > p-hydroxybenzoic > vanillic ≈ caffeic, and the ease of weathering of the minerals was calcic plagioclase > microcline > albite. Because of the conditions under which the experiments were performed, the amount of aluminum released on dissolution of the feldspars by the organic acids appeared to be related more to the strength of the acid than to its ability to form complexes with aluminum.
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