The application of chemical staining to separate calcite and aragonite minerals for micro-scale isotopic analyses.

Abstract

Staining is a useful laboratory tool for distinguishing specific carbonate minerals from a mixture of carbonates. Feigl's and Meigen's solutions are commonly used to distinguish aragonite from other carbonates. Feigl's solution stains the aragonite surface black and Meigen's stains purple, whereas the coexisting calcite remains nochang in color with either solutions. Both methods were applied to an authigenically precipitated carbonate chimney and a recrystallized metamorphic marble. Meigen's solution was favorable to stain fine and euhedral aragonites, but not effective for recrystallized aragonites. Feigl's solution was applicable to identify both types of aragonites. As a sample that demonstrates application of the Meigen's solution, isotopic analyses were carried out on aragonite and calcite separated from the seepage carbonate chimney collected from the Conical seamount of the Mariana forearc.