Open File Report 12
Mineralogy and geochemistry of mineralised and barren weathered
profiles, Parkinson Pit, Mt Magnet, WA
In both mineralised and barren profiles in the northern portion
of the Parkinson Pit at Mt Magnet, progressive zonation occurs from
a calcite (calcrete) zone through mica-rich and ferruginous assemblages
into chlorite-dolomite assemblages before passing into unweathered
pyrite-dolomite-siderite-bearing rocks. However, the barren profile
shows the development of Na- and Ca-rich micas rather than muscovite.
Ferruginization is more consistently present in the mineralised
The elements Co, Cu, Ni, Sc, Ti, W and Zn are associated with Fe
in highly ferruginous samples. The effect of discrete vertical zonation
is reflected by surface enrichment of Ca, Mg, Ba, Sr, Ga and Zr
and depletion in Co. However the most significant feature is the
association of Ag, As, Mo and Sb with Au in the weathered profile.
Readily mobilised elements like Co, Cu and Ni which occur within
the pyrite are associated with Fe and are not good pathfinders for
Weathering in the southern portion of the Parkinson Pit gives rise
to essentially similar mineralogical zonation to that in the north
except that a thick kaolinite blanket is developed in the top 20
m. Thus weathering conditions may have been more acidic in this
portion of the pit.
Last updated: Tuesday, January 04, 2000 12:10 PM