Improved fertilizer mineral compositions are provided by coating a mineral, such as gypsum, a member of the Kieserite Group, potassium magnesium sulfate, elemental sulfur, and mixtures thereof, with low pH maleic-itaconic copolymers. The preferred copolymers are aqueous dispersions of acid or partial salt maleic-itaconic copolymers, and are applied by spraying or other means onto the surface of the mineral and allowed to dry. The copolymer coatings increase the solubility of sulfate and calcium or magnesium ions from the fertilizer minerals, allowing accelerated plant availability and uptake of such nutrients.