Rockscape

What follows is a description of the brief mining history of the Mesoproterozoic-age Steenkampskraal monazite ore body located in southern Namaqualand, about 340 km north of Cape Town in South Africa. Steenkampskraal is a massive-lode ore body, possibly originating by igneous processes from an immiscible phosphate-sulphide-oxide magmatic liquid. The monazite ore occurs in a thin lenticular-shaped body surrounded by Mesoproterozoic granitic gneiss country rocks. The ore body is about 400 m in strike-length, extending about 450 m down-dip, with an average thickness of about 0.5 m.

The ore body was known to the early Bushman, who used the high-density monazite + apatite + magnetite ore for sling stones and arrowheads, and scattered artefacts such as stone flakes and core stones in the vicinity of the ore body. Samples from the ore body were first identified as monazite in 1949, and mining of monazite began in 1950 when a Vanrhynsdorp syndicate sunk three trenches about 5 m deep in the widest portions of the ore body. The first consignment of Steenkampskraal monazite ore was then exported from South Africa to the United Kingdom as a source of thorium. At about the time surface mining of monazite ore waned in early 1952, a crosscut from a vertical shaft located on the Steenkampskraal koppie intersected the ore body about 30 m below the surface.

In July 1952, a company named Monazite and Mineral Ventures Ltd. acquired the mineral rights from the Vanrhynsdorp mining syndicate, and undertook further development of the ore body. By July 1953, a residential area for the mine employees had been constructed at Steenkampskraal, and a specially designed processing plant was operating at the mine site. Full-scale underground mining also commenced at about this time, after an incline driven at an angle of 30 degrees for 140 m from the southern base of the Steenkampskraal koppie intersected the monazite ore body about 90 m beneath the surface. Mining continued until February 1959 when operations were suspended due to a lack of demand for thorium. The mine reopened in April 1962, and briefly operated for about a year, but operations finally ceased in 1963. Shortly after 1965, the processing plant and many of the surrounding buildings were dismantled, and Monazite and Mineral Ventures Ltd. ceased to exist.

Publications describing the occurrences and uses of thorium…

Out of the far western icefield of Western Dronning Maud Land (WDML) rise the Annandagstoppane nunataks. The name originates from the Norweigian word for the day after Christmas (i.e., Boxing Day) when these nunataks were first discovered.

There is not much rock exposure in East Antarctica, and little of that exposure is Archean in age. Three small and not very prominent Annandagstoppane nunataks have the distinction of exposing the only outcrops of Archean-age rocks in Antarctica outside of Enderby Land. (The largest of the three nunataks is shown in the photo, which was taken in 1995 when I was collecting samples for research purposes.) The three nunataks expose granitic rocks, informally described as the Annandagstoppane granite. These were the oldest known rocks in all of Antarctica until older rocks were identified in Enderby Land.

Is it possible that the Annandagstoppane granite is part of the basement upon which the younger Mesoproterozoic-age supracrustal rocks in the area were emplaced? After the breakup of Gondwana, did this part of East Antarctica retain a fragment of the Kaapvaal Craton?

Documentaries about Antarctica on DVD and Blu-ray…