Stability of kimberlite garnets exposed to chemical weathering: Relationship with Cr contents
The dissolution stability of garnets from kimberlite has been studied in new experiments in which etching in HF simulated natural chemical weathering. The experiments lasted 42 days and included weight loss monitoring and analysis of chemistry and parageneses of the output grains. The etched garnets of Cr2O3-rich parageneses became corroded less strongly. The greater chemical resistance of Cr-rich pyropes is consistent with the behavior of bulk Cr2O3 observed in a natural garnet assemblage from a weathered placer derived from the Mir kimberlite. Chemical weathering being the principal control of the assemblage composition, the placer assemblages with uncorroded pyropes may be compositionally proximal to their counterparts in the kimberlite.