Variation of Manganese Oxide Textures and Geochemistry with Rock Association at the Yakau Area, Ghana

Abstract

Twelve highly weathered residual oxide samples from outcrops at Yakau and Bofun near Dixcove show massive, vuggy, striations
of foliation, and fibrous-banded textures. The partially oxidised primary rock identified as amphibolite garnet – gneiss, which contains garnet 30%, amphiboles 35%, quartz 15% and ore minerals 5% with garnet partially replaced by recrystallised quartz
and manganese minerals, mainly pyrolusite. There are manganese oxide residuals that contain quartz 20%, todorokite and
pyrolusite 50%, goethite 30%, and garnet replaced by goethite. The vuggy textured residual oxide contains the highest manganese oxide (61.0 wt %), whereas the fibrous-banded type contains the least manganese oxide (1.8 wt %). It is recommended that stages of oxidation of the oxides be studied further to know the extent of maturity of oxides, which may contain higher MnO grades, as well as the textures of the oxides to be used as an additional tool for mineral exploration. Observations made from the scatter plots indicate a correlation coefficient of elements within the ores and rocks. The correlation coefficient (r) between some elements show a strong/positive correlation whereas others show a negative/weak correlation.