Origin of Material
Greenstone belts are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associate sedimentary rocks that occur within Archaean and Proteroziac cratons between granite and gneiss bodies. Greenstone belts are primarily formed of volcanic rocks, dominated by basalt, with minor sedimentary rocks inter-leaving the volcanic formations.
Approximate Mineral and Chemical Composition
The mineral assemblages of the samples are rich in greenschists and associated minerals. Greenschists is a generic name of minerals formed by regional metamorphism of mafic igneous rocks under the relatively low temperatures and pressures.
The name greenstone originates from commonly having an abundance of green minerals such as chlorite/chamosite, Actinolite/ and amphiboles and sheets-like minerals such as biotite/muscovite. The common minerals associated with greenschists include quartz, orthoclase and calcite.
The greenschists minerals are generally the pathfinders/ indicative of base metal sulphides and gold mineralisation.