TY - JOUR
A1 - Korges, Maximilian
A1 - Junge, Malte
A1 - Borg, Gregor
A1 - Oberthür, Thomas
T1 - Supergene mobilization and redistribution of platinum-group elements in the Merensky Reef, eastern Bushveld Complex, South Africa
JF - The Canadian mineralogist
N2 - Near-surface supergene ores of the Merensky Reef in the Bushveld Complex, South Africa, contain economic grades of platinum-group elements, however, these are currently uneconomic due to low recovery rates. This is the first study that investigates the variation in platinum-group elements in pristine and supergene samples of the Merensky Reef from five drill cores from the eastern Bushveld. The samples from the Richmond and Twickenham farms show different degrees of weathering. The whole-rock platinum-group element distribution was studied by inductively coupled plasma-mass spectrometry and the platinum-group minerals were investigated by reflected-light microscopy, scanning electron microscopy, and electron microprobe analysis.
In pristine ("fresh") Merensky Reef samples, platinum-group elements occur mainly as discrete platinum-group minerals, such as platinum-group element-sulfides (cooperite-braggite) and laurite as well as subordinate platinum-group elementbismuthotellurides and platinum-group element-arsenides, and also in solid solution in sulfides (especially Pd in pentlandite). During weathering, Pd and S were removed, resulting in a platinum-group mineral mineralogy in the supergene Merensky Reef that mainly consists of relict platinum-group minerals, Pt-Fe alloys, and Pt-oxides/hydroxides. Additional proportions of platinum-group elements are hosted by Fe-hydroxides and secondary hydrosilicates (e.g., serpentine group minerals and chlorite).
In supergene ores, only low recovery rates (ca. 40%) are achieved due to the polymodal and complex platinum-group element distribution. To achieve higher recovery rates for the platinum-group elements, hydrometallurgical or pyrometallurgical processing of the bulk ore would be required, which is not economically viable with existing technology.
KW - Bushveld Complex
KW - Merensky Reef
KW - PGE
KW - PGM
KW - supergene ores
KW - weathering
Y1 - 2021
U6 - https://doi.org/10.3749/canmin.2100023
SN - 1499-1276
VL - 59
IS - 6
SP - 1381
EP - 1396
PB - Mineralogical Association of Canada
CY - Ottawa
ER -
TY - JOUR
A1 - Genderjahn, Steffi
A1 - Lewin, Simon
A1 - Horn, Fabian
A1 - Schleicher, Anja M.
A1 - Mangelsdorf, Kai
A1 - Wagner, Dirk
T1 - Living lithic and sublithic bacterial communities in Namibian drylands
JF - Microorganisms : open access journal
N2 - Dryland xeric conditions exert a deterministic effect on microbial communities, forcing life into refuge niches. Deposited rocks can form a lithic niche for microorganisms in desert regions. Mineral weathering is a key process in soil formation and the importance of microbial-driven mineral weathering for nutrient extraction is increasingly accepted. Advances in geobiology provide insight into the interactions between microorganisms and minerals that play an important role in weathering processes. In this study, we present the examination of the microbial diversity in dryland rocks from the Tsauchab River banks in Namibia. We paired culture-independent 16S rRNA gene amplicon sequencing with culture-dependent (isolation of bacteria) techniques to assess the community structure and diversity patterns. Bacteria isolated from dryland rocks are typical of xeric environments and are described as being involved in rock weathering processes. For the first time, we extracted extra- and intracellular DNA from rocks to enhance our understanding of potentially rock-weathering microorganisms. We compared the microbial community structure in different rock types (limestone, quartz-rich sandstone and quartz-rich shale) with adjacent soils below the rocks. Our results indicate differences in the living lithic and sublithic microbial communities.
KW - lithobiont
KW - intracellular DNA
KW - extracellular DNA
KW - weathering
KW - dryland
KW - rock
Y1 - 2021
U6 - https://doi.org/10.3390/microorganisms9020235
SN - 2076-2607
VL - 9
IS - 2
PB - MDPI
CY - Basel
ER -