Abstract

The occurrence of loughlinite (Na-sepiolite) in two pans (Koi Pan and Brak Pan) of the Northern Cape Province is reported upon. The presence of loughlinite within the pan sediments was confirmed by means of X-ray Diffraction analysis, which showed distinct reflections at 12.7 to 12.8 Å, which collapsed to 12.3 Å following Mg-saturation. This is the fourth reported occurrence of loughlinite worldwide and the first from South Africa. Loughlinite occurs associated with the mineral analcime, which was also reported from all previously described occurrences of the former. It is also interesting to note that all known occurrences of loughlinite are from playa-lake settings. We propose that the mineral formed authigenically under the saline and alkaline conditions of the pan environment, as is also deemed to have happened by some scholars in the Killik area, Turkey. Loughlinitization of sepiolite from sepiolite-bearing Kalahari calcrete occurring within the study area appears unlikely.

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