Open File Report 13
Mineralogical and geochemical studies of gossan and wall rocks,
Bottle Creek, Western Australia
Samples of surface gossan from Emu, VB and Boags (VB South) prospects,
and of subsurface gossan and mineralized weathered wall rocks from
diamond drill core at Emu and VB prospects have been examined mineralogically
Mineralogy consists of quartz, muscovite, kaolinite, goethite,
hematite in variable quantities with subordinate talc, rutile, tourmaline
and manganese oxides. Secondary minerals of the jarosite and alunite
supergroups are common in the gossans and wall rocks respectively.
Pyrite is the predominant sulphide in protore with minor tetrahedrite,
sphalerite, arsenopyrite, marcasite and magnetite.
Anomalous concentrations of Ag, As, Au, Cu, Pb, Sb and Zn in protore
are reflected in gossan and mineralized wall rocks, although there
is a marked depletion at the surface. These elements are therefore
considered to be reliable pathfinder elements. Concentrations of
Hg, Te and Tl are also considered anomalous, but because of low
absolute values and difficulty of analysis, are not considered to
be viable pathfinder elements. The nature of concentrations of Mn,
Ti, B and Ba within the mineralized horizon is not yet established
and analysis of both mineralized and unmineralized country rocks
is necessary before they can be considered as pathfinder elements.
Lack of geochemical anomalies in soils supports previous observations
(van der Heyde, 1988) that the regolith stratigraphy at VB is transported
and represents colluvial-alluvial material on the floor of a drainage
channel. Additional research relevant to present and longer-term
exploration is indicated.
Last updated: Tuesday, January 04, 2000 12:26 PM