The partition coefficient for Ba²⁺ into calcite has been established as 0.06 ± 0.01 at 25°C (77°F). The partition coefficient proved independent of rate of precipitation in a series of 19 runs of varying duration. This value is substantially lower than that reported by Kitano in 1971, reflecting our seeding technique, which focused the experiment on crystal growth rather than on spontaneous nucleation and growth. The 0.06 value is compatible with the values reported for Sr²⁺ (0.05 to 0.14), a cation of identical charge, but closer to Ca²⁺ in ionic radius.

The natural partitioning of Ba²⁺ was examined in fresh (aragonite) and altered (calcite) corals from the Pleistocene reef terraces exposed on Barbados, West Indies. The Ba²⁺ concentrations ranged from 8 to 15 ppm in the aragonites and decreased to typical values of 1 to 3 ppm in the calcites. The partitioning of Ba²⁺ in these samples was quantitatively similar to the attendant partitioning of Sr²⁺. The partitioning of Ba²⁺ during the carbonate cycle offers new areas of investigation. The low concentrations of Ba²⁺ in sedimentary biograins (3 orders of magnitude less than Sr²⁺) make Ba²⁺ a sensitive monitor of externally derived, barium-bearing solutions involved in diagenetic reactions. Likewise, t e low concentrations ensure ideal partitioning behavior in diagenetic solutions of low ionic strength.

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