THERMAL TRANSFORMATIONS OF SOME STRONTIUM-BEARING ARAGONITES

The aragonite-calcite transformation of a series of nine natural arago nites was investigated using DSC and TG. Chemical analysis indicated s ubstitution predominantly by strontium in the range of 0.008 to 1.04%. The specimens each produced a weak endotherm between 420-degrees and 505-degrees-C. The enthalpy of transition was found to increase with t he level of substitution, the aragonite structure apparently stabilise d by strontium. Moreover the TG curves showed that in a number of case s the solid solution structure contained up to 0.45% occluded water wh ich was released during the transformation.