A study of a magnesite mineralisation and its potential environmental impact in the Tshipitse Magnesite Field, Limpopo Province of South Africa

Abstract

This study sought to determine the mineralisation of magnesite in the Folovhodwe, Venmag and Nyala Mines in the Tshipise area of the Limpopo Province in South Africa. The main aims of the study were to characterise the geology of the discussed mines, and to estimate the economic potential of extracting magnesite from the waste dump rocks and the impact of the Venmag Mine on environmental soil and surface water. Data were collected using the following methodologies: Field observation, Sampling and Laboratory work that comprised microscopy, X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Inductively Couples Plasma-Optical Emission Spectrometry (ICP-OES). The study focused specifically on: (1) The source rocks of the magnesite ore; (2) The mineralisation type of magnesite; (3) The role of the dolerite dykes, sills, and structures on the mineralisation of magnesite; (4) The economic potential of the in situ magnesite and re-use of the waste rock dumps; and (5) The quality of environmental water and soil. The researcher found that: (1) The magnesite host rock is ultramafic, rather than doleritic, as previously thought; (2) The magnesite mineralisation occurs as veins and is controlled by structures such as bedding plans and joints; (3) The geological sequential order is generalised as ultramafic rocks → dolerite dykes and sills → thermal water circulation → formation of magnesite veins; (4) The resource evaluation indicates mineable magnesite, both in-situ and from the waste rock dumps; (5) The waste dump rocks may be used for neutralising acid mine drainage due to their high alkalinity, or for road construction and bricks making due to their physical characteristics; (6) The water quality from the Venmag Mine pits and the Nwanedi River were not significantly impacted by magnesite mining activities during the season of this study; and (7) There was no major contamination of heavy metals from the waste rock dumps and their surrounding soil at the time of the study. The researcher recommends that a study be done for the age of the magnesite mineralisation as well as the doleritic rocks, and reprocessing of the magnesite waste rock dumps economically and technically in the Nyala, Venmag and Folovhodwe Mines