Abstract

The dissolution of calcium carbonate with both organic and aqueous solvents was examined quantitatively and kinetically. Neither ethanol and nor acetone at 25 degrees C dissolved appreciable aragonite or calcite, even after nearly ten days. Bleach (sodium hypochlorite) was a much less effective solvent than deionized water, producing little or no net calcium in solutions in contact with calcium carbonate. Although exposure to sodium hydroxide solutions also yielded relatively small concentrations of calcium in the fluid, characterization of the exposed carbonate grains by X-ray powder diffraction and by light microscopy revealed extensive replacement of the CaCO 3 by Ca(OH) 2 , calcium hydroxide (portlandite). A solution of Alconox TM , a commercial laboratory anionic detergent, was about half again as potent as deionized water, and hydrogen peroxide proved to be many times more corrosive of calcium carbonate than deionized water. These results are consistent with published and anecdotal observations of the effects of laboratory preparation protocols on calcium carbonate. Our quantitative data permit the researcher to assess the potential for a treatment procedure using any of these solutions to compromise the integrity of a sample of calcium carbonate.

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