Honours Field School report

The Stellenbosch University Honours class of 2018 made the great trek (by overnight bus) up from the Cape to the exciting geology of the Kaapvaal craton. A total of twenty students from both the hard rock geology- and environmental geochemistry- streams partook in the tour, which focussed predominantly on various mines located in Gauteng, Mpumalanga, North West and Limpopo provinces. The tour was led by Dr Bjorn von der Heyden, with invaluable assistance provided by Masters student Stephan Dunn. First stop on the tour was the Vredefort Dome, a must-see for any geological excursion upcountry. A transect through the collar provided students with their first practical exposure to the Wits stratigraphy, including a brief stop at the auriferous Amazon Reef conglomerate. The highlights of the visit to the Vredefort dome however, were undoubtedly the various impact features that were observed (shatter-cones and pseudotachalyte breccias). Stop two was in the Johannesburg commercial district, where Matt Mullins from Tecoma Strategies (and a Stellenbosch University guest lecturer) provided the students with critical insights into the business aspects of geology and into the importance of geology to the minerals industry. The next stop was at Exxaro’s North Block Complex open cast coal mine in the Highveld coal field. For many of the students, this was their first ever exposure to a mining environment and the Exxaro team did an outstanding job of introducing students to coal mining and to the role of the geologist in the mine value chain.

The trip to Barberton comprised a necessary detour via Tjarkastad to investigate the spinifex textures and pillow lavas of the Onverwacht Group komatiites and komatiitc basalts respectively. Once in Barberton, an action-packed itinerary included tours of the Golden Quarry (courtesy of Sheba Mine), a tour of the BIOX recovery plant (Fairview Mine), and underground excursion in the Scotia Mine (Chamotte Holdings), and several hours spent evaluating the numerous exciting stops on the Mokahanje Geotrail. Students also benefitted greatly from their evening interactions and discussions with their contemporaries from UKZN- who were also staying at Digger’s retreat in Barberton whilst we were there. Saturday was spent experiencing some of the impressive geological features of the Eastern Limb (including the Dwarsrivier UG1 outcrop, a breccia pipe, and the Magnet Heights outcrop), whereas Sunday was a more touristic tour along the escarpment with stops at Pilgrim’s Rest, Pinnacle Falls, Bourke’s Luck Potholes, and the Wolfberg Group stratigraphy).

Week two kicked off with two exciting mine tours in the Phalaborwa Igneous Complex at Foskor and at Phalaborwa Mining Company. The students were thus able to experience both open cast and underground mining, and both mines provided exceptional explanations of their mine water treatment programs (thereby satisfying the intrigues of our Environmental Geochemistry students). A trip up to the Northern Limb of the Bushveld Igneous Complex included a tour of the Zaaiplaats Sn mineralisation in the Bobbejaankop granites, and road cut observations of the Rooiberg ignimbrites and Waterberg basal conglomerates (all courtesy of Bushveld Minerals). Our final two days comprised an impromptu visit to a Rustenberg Grey quarry, a detailed mine tour of the Vergenoeg fluorspar pipe (Minersa), and some exceptional viewing of Wits mineralisation in opencast exposures and of tailings retreatment operations (Mintails Mining).

All companies and individuals who made this tour a great success are thanked gratefully by the staff and students of Stellenbosch University. Your time, explanations, and expertise all contributed to an exciting, practical, and memorable learning experience for our students. Thank you.