Duncan Miller

This month we are going to do all three, recycle an old publication, reuse it with additional photographs, and repurpose it as an article on the club’s website. The article describes Cape Town’s former tin mines, and the website article has a virtual tour of the Vredehoek tin mine on Devil’s Peak, courtesy of Dr Gregor Borg of Halle University in Germany. All of this is available for download from http://ctminsoc.org.za/resources/CAPETOWNSTINMINES.pdf

Few people know that there were two early 20th century tin mines in the vicinity of Cape Town. The deposit first mined at the turn of the century was on the farm Annex Langverwacht 245 near Kuils River. Most of the production was from alluvial deposits, producing over 700 tons of cassiterite (SnO2) until the intermittent working ceased in 1956. The visible remains of mining include various trenches and shafts, sunk into or near the ore lodes. The primary tin-bearing lodes from which the alluvial cassiterite weathered consist of aplite dykes (fine-grained granitic rock) and quartz veins, in a zone about 500 m wide. The quartz veins reportedly contain molybdenite, wolframite, cassiterite, arsenopyrite, tourmaline, mica, and quartz. These veins are similar in mineralogy to others located in the metamorphosed sediments of the Malmesbury Group around Durbanville and in granites in the Helderberg area. Clearly this mineralisation is related directly to the intrusion of the Cape Granites.

In 1909 cassiterite was discovered in a stream above Vredehoek on Devil's Peak. Mining here started in 1911, but had ceased by 1916 after producing an estimated total of about 4 tons of concentrate. The visible remains include the concrete flumes for concentrating the dense cassiterite, as well as beautifully constructed retaining walls, a blocked vertical shaft some 55 m deep, and an accessible horizontal adit penetrating the Malmesbury Group rocks about 100 m. The mineralised zone is about 8 m wide and consists of a series of thin quartz veins with crystals of dark reddish-brown cassiterite near their margins and between the constituent interlocking quartz grains. Here the mineralisation is over a kilometre from the granite-Malmesbury contact, but no doubt also owes its existence to the intrusive Cape Granite.

An adit at the former tin mines on Zevenwacht Farm on the Eerste River Hills (photograph by Amour Venter)

The neatly constructed walling at the former Vredehoek in mine on Devil’s Peak