The geology of the Zambia Broken Hill mine, Kabwe

Abstract

The Zambia Broken Hill ore deposits occur within a belt of dolomitic rocks of Katanga age (Upper Precambrian), which strikes NW and is flanked by shale and phyllite. The main pipe-Iike orebodies, striking WSW, and plunging to the ENE, have a massive sulphide core, consisting of sphalerite, galena and pyrite, surrounded by an oxidised zone containing willemite, smithsonite and cerrussite. An antipathetic relationship exists between lead and iron in the sulphide ore. The wall rock, a pure massive dolomite, was brecciated during oxidation. The breccia matrix consists of jasper-like lithified mud with erratic fragments of oxidised ore. A similar lithified mud is common along the outer margins of the oxidised ore, where it was emplaced through late infilling of cavities.