The Century zinc-lead-silver deposit has a geological
resource of 118 million tonnes averaging 10.2% zinc, 1.5% lead and 36 g/t
silver. It lies approximately 250 krn NNW of Mt Isa in NW Queensland, Australia,
and is hosted by middle Proterozoic age siltstones and shales of the Lawn Hill
Formation. Within the orebody, most mineralisation occurs selectively within
black shale units as fine grained sphalerite and galena lamellae with minor
pyrite and siderite. The black shale units are separated by weakly mineralised
sideritic siltstone horizons. The deposit is unmetamorphosed and only weakly
deformed, displaying excellent lateral stratigraphic and grade continuity.
The deposit is mostly overlain by younger Proterozoic
sediments and later Cambrian age limestone cover and only a small proportion of
the mineralisation crops out. Mineralisation has a subtle surface expression
without a classic gossan profile, probably due to the low iron sulphide content
of the ore. These factors contributed materially to the length of time between
the first recognition of lead-zinc-silver mineralisation in the area by
prospectors in the 1880s, to the discovery of the orebody by CRA Exploration Pty
Ltd (CRAE) in April 1990.

Small scale prospecting and mining continued in the area
from the date of the first mining lease in 1887. Post 1950, the deposit area was
also included within nine separate regional exploration titles prior to CRAE's
title acquisition in 1987. CRAE's original exploration strategy was partly
pragmatically and partly conceptually inspired, but the eventual discovery only
partly conformed to the original conceptual model. The deposit was found higher
in the stratigraphy than the original target position, with unexpectedly low
total sulphide content relative to other known deposits.

The discovery soil anomaly was
located by the CRAE's first regional orientation traverse line in the area, but
was not drill tested for three years. The discovery sequence at Century has
strong elements of persistence, technical competence and some luck. It
demonstrates that even in well explored terrains (by conventional standards) the
exploration story can never be said to be over. The foreshadowed development of
an economic resource at Century will hopefully inspire continued commitment to
'brownfields' exploration by mining companies, and demonstrate to external
regulators theimportance of
genuine multiple land use strategies and the need for continued access to land
for exploration and mining purposes.