Occurrence of Hardened Matters in the Andosolic Cover from the Western Highlands of Cameroon: Case Study of Those Risen on Trachyte in the Southern Side of the Bambouto Mountains

The aim of the present study is to acquire knowledge about the hardened materials present in the andosolic cover from the Bambouto Mounts. For that purpuse, petrographic, mineralogical, and geochemical characteristics of the hardened materials, isalteritic blocks, and the parent rock were investigated in order to put into relief the different facies found, the genetic relationship between those geological matters, and the mechanism governing the formation and the evolution of the hardened materials found in the Andosols from the Bambouto mounts. These matters have low thickness, are highly hardened, with different aspects and locations. They are present within the soils, at the point of emergence of streams, on the flatty areas on top of hills and at the foot of interfluves. Microscopically, their plasmas are respectively isotic and cristic. Gibbsite, goethite, and halloysite are respectively their main minerals. Geochemically, both facies are highly aluminous. During the weathering, Sanidine changes sequentially into Allophane, Halloysite, and Gibbsite; Pyroxen and Ilmenite for their own contribute to the formation of Goethite. There is a direct genetic relationship between the hardened materials, the isalteritic blocks, and the parent rock. The uphill position is the eluvial part and the downhill position the illuvial part; this generates the evolution of the hardened materials from their translucent initial status towards their reddening and tanning final status. The characteristics of the hardened materials make them bauxitic hardened materials, organized into two different facies: A lithorelictuel and a vitreous facies. The presence of those hardened materials in the Andosols from the Western Highlands of Cameroon is harmful for farming. The present study is then a high contribution to the management of the mine ore deposit within the Western Highlands of Cameroon.