The St Lucia Experience

This article summarises publicly available geological, sedimentary, RBM and export evidence relating to the Black and White uMfolozi catchments and the possible transport of mineral-bearing material into the lower uMfolozi and St Lucia Estuary system.

The information is divided between:

1. Minerals directly documented in the catchment geology;

2. Mineral components that could be transported downstream through erosion and flooding;

3. Minerals and products publicly associated with Richards Bay Minerals;

4. Relevant South African export records; and

5. Export-control information.

1. White uMfolozi catchment

The White uMfolozi Inlier, including the Denny Dalton and Mozaan Group geological areas, contains documented localised gold- and uranium-bearing conglomerates.

Minerals and mineral-bearing phases documented in the White uMfolozi geological records include:

Gold;
Uranium-bearing minerals;
Brannerite;
Uraniferous leucoxene;
Uraninite;
Coffinite;
Pyrite;
Quartz;
Chert;
Sericite;
Quartz-rich sandstone and quartz arenite;
Conglomerate containing quartz and pyrite;
Banded iron formation in the wider Mozaan succession; and
Heavy-mineral assemblages derived from granitoid-greenstone source rocks.

The documented mineralisation is described as localised, erratic, low-grade and limited in tonnage. The available studies do not provide a complete catchment-wide mineral inventory or downstream concentration measurements.

The provenance evidence identifies granitoid-greenstone source rocks west of the White uMfolozi Inlier.

2. Black uMfolozi catchment

The Black uMfolozi headwater region is associated mainly with Karoo and Dwyka-related geological units.

The relevant geological materials include:

Tillite;
Shale;
Siltstone;
Sandstone;
Basalt;
Doleritic material; and
Coal-bearing formations.

Mineral components that may be derived from the weathering and erosion of these rocks include:

Quartz;
Feldspar;
Mica;
Clay minerals;
Iron oxides and hydroxides;
Iron-bearing silicate minerals;
Ferromagnesian minerals from basalt and dolerite;
Possible magnetite or titanomagnetite;
Possible pyrite or other sulphide minerals in some shale- and coal-associated settings; and
Coal and carbonaceous material.

Coal and carbonaceous material are geological resources but are not mineral species in the strict mineralogical sense.

The public geological sources reviewed do not provide a complete mineral assay for the Black uMfolozi catchment or confirm economic concentrations of gold, uranium, titanium minerals, magnetite, zircon or rare-earth elements in the headwaters.

3. Minerals that could be transported downstream

Through weathering, erosion, flood mobilisation and sediment transport, the combined Black and White uMfolozi system could carry a mixture of mineral and organic materials downstream.

The possible downstream mineral components include:

Quartz;
Feldspar;
Mica;
Clay minerals;
Iron oxides and hydroxides;
Iron-bearing silicate minerals;
Pyrite;
Magnetite or titanomagnetite, if present in the eroding source rocks;
Ilmenite, if present in the heavy-mineral fraction;
Zircon, if present in the heavy-mineral fraction;
Gold-bearing pyrite grains, if eroded from the White uMfolozi mineralised conglomerates;
Uranium-bearing grains, if eroded from the White uMfolozi mineralised conglomerates;
Brannerite, uraninite, coffinite or uraniferous leucoxene, if physically released from mineralised White uMfolozi units;
Chert;
Sericite;
Banded iron formation-derived material;
Organic carbon;
Plant debris;
Reed-derived material; and
Nutrients or contaminants associated with sewage, agriculture and disturbed floodplain soils.

The presence of a mineral in a catchment source rock does not by itself establish its concentration in downstream mud or estuary sediment. Downstream transport would depend on the mineral’s grain size, density, resistance to weathering, flood conditions, channel position and sediment-trapping processes.

4. Sediment transport and floodplain conditions

Research on the lower Mfolozi records suspended sediment with an average median particle size of approximately 0.0052 mm, representing very fine silt.

The average median size of reported bed-load material was approximately 0.35 mm, representing medium-grained sand.

The lower Mfolozi and Msunduzi system has been affected by:

Floodplain canalisation;
Wetland drainage and removal;
Levees;
Altered flood pathways;
Changed sediment-trapping conditions; and
Historical changes to the estuary-mouth connection.

In 1952, a separate Mfolozi mouth was created approximately 1.5 km south of the St Lucia mouth to reduce the entry of Mfolozi sediment into the St Lucia system.

Fine suspended sediment and coarser bed-load material may carry different mineral assemblages. Heavy minerals, if present, may become concentrated in particular coarse-sand deposits, channel bars, flood layers or other depositional environments rather than being evenly distributed throughout soft mud.

5. Richards Bay Minerals

Richards Bay Minerals publicly describes itself as a heavy-mineral-sands producer operating in northern KwaZulu-Natal.

RBM’s public product descriptions identify the following products or mineral-bearing products:

Ilmenite;
Rutile;
Zircon;
Iron;
Pig iron;
Ferrous metallics;
Titanium dioxide slag;
Titania slag; and
Titanium dioxide products.

The RBM public profile describes production as predominantly involving zircon, rutile, iron and slag. A South African government report concerning the Zulti South project identifies RBM products as zircon, rutile, ilmenite and titanium dioxide.

The public RBM product information reviewed does not list the following as stated principal RBM products:

Gold;
Uranium;
Brannerite;
Uraninite;
Coffinite;
Pyrite;
Chert;
Sericite;
Feldspar;
Clay minerals; or
Rare-earth concentrates as a principal product.

The public records reviewed do not establish that RBM holds rights to the White uMfolozi gold-uranium mineralisation or that RBM products originated from uMfolozi catchment sediment.

6. South African export categories

The following customs categories were used for comparison:

HS 2614: Titanium ores and concentrates;
HS 261510: Zirconium ores and concentrates;
HS 2616: Precious-metal ores and concentrates;
HS 2612: Uranium or thorium ores and concentrates;
HS 2846: Compounds of rare-earth metals, yttrium or scandium;
HS 7108: Gold in unwrought, semi-manufactured or powder form;
HS 2601: Iron ores and concentrates; and
HS 261790: Other ores and concentrates.

These customs categories are broad. They do not identify the exact mineral species, mine, geological source, exporter, mining-right holder or receiving company.

7. South African exports to the world in 2024

The latest complete national data reviewed for 2024 records approximately:

Titanium ores and concentrates, HS 2614:

Approximately 806,494 tonnes;
Approximately US$591.3 million;
Quantity marked as estimated in the source.

Zirconium ores and concentrates, HS 261510:

Approximately 556,974 tonnes;
Approximately US$610.2 million.

Precious-metal ores and concentrates, HS 2616:

Approximately 16,876 tonnes;
Approximately US$1.003 billion;
Aggregate category that may include gold, silver and platinum-group material.

Rare-earth compounds, HS 2846:

Approximately 288 tonnes;
Approximately US$5.5 million;
Processed-compounds category, not a direct measure of raw rare-earth ore.

Uranium or thorium ores and concentrates, HS 2612:

Approximately US$2 million in reported value;
Quantity not reported in the 2024 record reviewed.

Gold, HS 7108:

Approximately US$8.17 billion in reported value;
National gold exports in various forms;
Not attributable to the uMfolozi catchment from the customs data alone.

8. South African exports to Australia in 2024

The 2024 trade data reviewed records approximately:

Titanium ores and concentrates:

200 kg;
Approximately US$144,000.

Zirconium ores and concentrates:

437,729 kg, or approximately 438 tonnes;
Approximately US$858,000.

Rare-earth compounds:

6,455 kg, or approximately 6.5 tonnes;
Approximately US$81,000.

Precious-metal ores and concentrates:

41 kg;
Approximately US$4,500.

Uranium or thorium ores:

No reported Australian-destination quantity in the 2024 record reviewed.

Gold under HS 7108:

No reported Australian-destination quantity in the 2024 record reviewed.

The South African zirconium-ore export records to Australia reviewed show approximately:

2018: 1,011 tonnes;
2019: 1,249 tonnes;
2020: 1,142 tonnes;
2021: 1,219 tonnes;
2022: 628 tonnes;
2023: value recorded but quantity not reported; and
2024: approximately 438 tonnes.

These records demonstrate a South Africa-to-Australia trade stream in zirconium ores or concentrates. They do not identify the exporter, mine, shipment, port, product batch or geological origin.

9. Export controls and permits

The International Trade Administration Commission states that selected South African tariff lines are subject to export control.

Export controls may relate to:

Environmental requirements;
Safety;
Security;
Technical requirements;
International agreements; and
Beneficiation requirements.

The relevant SARS restricted-goods information identifies uranium ores and concentrates under HS 2612.10 as controlled goods.

The public records reviewed do not provide a single database showing, for every shipment:

The exporter;
The mining-right holder;
The export-permit number;
The exact mine of origin;
The geological source;
The receiving company;
The product batch;
The mineral composition; or
The relationship between a shipment and any particular catchment.

10. Evidence needed to establish downstream origin

To establish whether a particular mineral or sediment sample originated in the Black or White uMfolozi catchment, the relevant evidence would include:

Representative samples from the White uMfolozi;
Representative samples from the Black uMfolozi;
Samples from the lower uMfolozi;
Samples from St Lucia Estuary depositional areas;
Grain-size analysis;
Heavy-mineral separation;
X-ray diffraction;
X-ray fluorescence;
ICP-MS or ICP-OES;
Gold analysis;
Uranium and thorium analysis;
Titanium, iron and zirconium analysis;
Rare-earth element analysis;
Magnetic susceptibility testing;
Radiation screening;
Comparative mineral fingerprints;
Sediment transport and flood-deposition records;
Mining-right and prospecting-right records;
Environmental authorisations;
Waste-disposal records;
Customs declarations;
Export permits;
Port and shipping records; and
Exporter and receiver documentation.

Conclusion

The public evidence documents:

Gold- and uranium-bearing mineralisation in localised White uMfolozi geological units;
Uranium-bearing phases including brannerite, uraninite, coffinite and uraniferous leucoxene in the documented White uMfolozi mineralised setting;
Quartz, chert, pyrite and sericite in the White uMfolozi geological records;
Quartz, feldspar, mica, clay minerals and iron-bearing materials associated with the wider Black uMfolozi geological setting;
Coal-bearing formations in the wider Black uMfolozi headwaters;
Possible downstream transport of heavy minerals and iron-bearing material through erosion and flooding;
RBM production of ilmenite, rutile, zircon, iron and titanium-related slag and products;
Large national South African exports under titanium-ore and zirconium-ore customs categories;
A documented South Africa-to-Australia trade stream in zirconium ores or concentrates; and
Export controls applying to selected mineral categories, including uranium ores and concentrates under HS 2612.10.

The public records reviewed do not identify the exact mineral composition of downstream St Lucia sediment, the exact origin of any particular sample, the identity of an exporter or receiver, or a direct connection between the uMfolozi catchments and RBM export shipments.

Please consider this information for independent geological, environmental, customs and investigative review.

Source links

University of KwaZulu-Natal geological study:

https://researchspace.ukzn.ac.za/items/8b259f10-abd6-4900-a7b4-2d45da7161c3

Additional University of KwaZulu-Natal research record:

https://researchspace.ukzn.ac.za/items/eef877f2-8a0b-45e7-b043-d1f9d1f8c407

ResearchGate record for the Sinqeni Formation study:

https://www.researchgate.net/publication/262380816_Stratigraphy_and_provenance_of_the_auriferous-uraniferous_fluvial_to_shallow-marine_Sinqeni_Formation_Mozaan_Group_northern_KwaZulu-Natal_South_Africa

South African Journal of Geology record:

https://pubs.geoscienceworld.org/gssa/sajg/article/115/3/327/141388/STRATIGRAPHY-AND-PROVENANCE-OF-THE-AURIFEROUS

Richards Bay Minerals official profile:

https://www.riotinto.com/en/operations/africa/richards-bay-minerals