| dc.description.abstract | The predominantly pyrite - pyrrhotite Bukura and Mbesa
mineralisation occurs in the Kakamega District of the Western
Province of Kenya. The study area in which this mineralisation
occurs covers approximately 244 km immediately to
the south-west of Kakamega Town and is part of degree sheet
33 S.E. Quadrant. In studying the mineralisation, geological
field mapping of the study area was carri d out at a scale of
1:50,000 and a geological map compiled at a scale of 1:25,000.
This was followed by core logging of two drill cores DHYA2
and DHYA3c sunk into the Mbesa mineralisation zone. Laboratory
work involving study of rock samples in thin section
under the microscope, X-ray diffraction analyses, study of
polished sections using the ore microscope and X-ray fluorescence
element analyses pf samples from the two cores to find the major r. -
elements present and also whether any traces of gold are associate-
ted with the mineralisation, was subsequently carried out. The .. ::
Bukura and Mbesa sulphide-mineralisation occurs mainly in steeply
dipping.Kavirondian mudstones and to a lesser extent grits at
the contact of the Mumias granite. The mineralisation is charar
cterized by the sulphides; pyrite, pyrrhotite, sphalerite and
chalcopyri te in order of abundance. Gangue minerals are cha.racterized
mainly by~hornblende, chlorite, micas, epidote, clinozoisite
and tremolite - actinolite. The mineralisation is of a
hydrothermal nature and the water of the hydrothermal fluids in
these contact zones is considered to have been primarily magmatic
and metamorphic in origin .. A larger fraction of the sulphur,
iron, zinc and copper of the sulphides is considered to have been
derived from the host rocks and a lesser portion of these constituents
from the Mumias granite itself. The energy required to
drive the hydrothermal system responsible for the Bukura and | en |
