We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Mineralogy and mineral paragenesis of the Palaeoproterozoic manganese ores of the Avontuur deposit of the Kalahari Manganese Field, South Africa.
- Authors
Coetzee, L. L.; Gutzmer, J.; Smith, A. J. B.; Beukes, N. J.
- Abstract
This study provides for the first time details of the mineralogy, petrography and mineral paragenetic relationships of manganese ores of the Avontuur deposit, a prominent northern outlier of the Kalahari Manganese Field in the Northern Cape Province of South Africa. Using a combination of light and electron microscopy and X-ray powder diffractometry on an extensive suite of exploration drill core samples, it is shown that the manganese ores comprise an exceptionally fine-grained assemblage of Mn2+-silicates (friedelite, tephroite, gageite), Mn2+/Mn3+-oxides (jacobsite, hausmannite) and Mn2+-carbonates (rhodochrosite, kutnahorite, Mn-dolomite and Mn-calcite). This mineral assemblage is a product of diagenesis and very low-grade regional metamorphism. Locally, this assemblage is overprinted by contact metamorphism or supergene alteration. Despite close geochemical and textural similarities, the manganese ores of the Avontuur deposit are surprisingly different in their mineralogy compared to the carbonate- and braunite-dominated mangano-lutites of the main Kalahari deposit. Distinctly higher concentrations of both SiO2 and Fe2O3 in the manganolutites of the Avontuur deposit as compared to the main Kalahari Deposit provide the reason for the markedly different mineralogy. Such marked differences in bulk chemistry are tentatively attributed to systematic lateral variations in the physicochemical conditions of mineral precipitation during the deposition of the Hotazel Formation.
- Subjects
SOUTH Africa; NORTHERN Cape (South Africa); MANGANESE ores; MINERALOGY; ORE deposits; MINERALS; PARAGENESIS; DRILL cores
- Publication
South African Journal of Geology, 2024, Vol 127, Issue 1, p31
- ISSN
1012-0750
- Publication type
Article
- DOI
10.25131/sajg.127.0016