Stewart R. Wallace — 1919–2009 - Society of Economic Geologists

EXPLORATION REVIEWS
42 SEG NEWSLETTER No 78 JULY 2009
... from 41
Exploration Reviews (Continued)
SOUTH AUSTRALIA
Oz Minerals’ Prominent Hill IOCG
mine commenced production in Febru -
ary, with first copper-gold concentrates
being railed out to Darwin for export.
Resources continue to expand at the
deposit, with the most recent drilling
campaign increasing the “Western
Copper” deposit by 32% to 245 kt of
contained copper. Inferred Resources at
the Western Copper deposit now stand
at 14.5Mt @ 1.7% Cu, 0.28g/t Au and
3.7 g/t Ag. Total resources at Prominent
Hill stand at 283.2 Mt @ 0.9% Cu, 0.8
g/t Au and 2.5 g/t Ag (2.5 Mt Cu, 7.4
Moz Au, and 22.6 Moz Ag). Oz Minerals
plans to produce 85 to 100 kt of copper
and 60 to 70 koz of gold in concentrates
in 2009. The deposit remains open to
the east, west, and at depth.
An interesting aside to the success of
Prominent Hill (discovered by Minotaur
Resources in 2001) is the fact that it was
perceived to be “the jewel in the crown”
in the Oz Minerals stable (which
included the Rosebery, Century, and
Golden Grove base metal mines in
Australia and the Martabe gold project
in Indonesia) during the recent takeover
negotiations with the China Minmetals
Group. The Foreign Investment Review
Board of thefederal government
approved the takeover but ruled that
the Prominent Hill mine should be
excluded from the takeover on national
security grounds as it was located
within the vast Woomera rocket rang;
hence, Prominent Hill remains with Oz
Minerals, while most of the other assets
are now owned by Minmetals.
BHP Billiton is seeking the approval
of the Australian, South Australian,
and Northern Territory governments for
a significant expansion of its existing
mining and processing operation at
Olympic Dam in northern South
Australia. The Olympic Dam mine
produces copper, uranium, gold, and
silver from a massive IOCG deposit.
It is the world’s fourth largest copper
and gold deposit, and the largest uranium
deposit. It also contains significant
quantities of silver. The proposed
expansion would be a progressive
development, requiring construction
activity over a period of 11 years.
The company plans for the new open
pit mine to operate simultaneously with
the existing underground operations—
and remember that the deposit is buried
under 300 m of younger cover rocks!
Once the new expansion is completed,
mining rates will increase to 72 Mtpa,
compared to the current mining rate of
12 Mtpa from the underground operations.
This will produce 2.4 Mt of copper
concentrate each year and 750 kt of
refined copper, along with 19 kt of uranium
oxide, 800 koz of gold bullion and
2.9 Moz of silver bullion.
WESTERN AUSTRALIA
In recent years, companies have
explored beneath the oxide gold
deposits in the WA deserts for primary
gold deposits, and at its DeGrussa
prospect in the Meekatharra district,
Sandfire Resources has hit the jackpot.
A program of 30 reverse circulation drill
holes was completed to teat for depth
extensions to a 220-m-long zone of previously
discovered oxide gold mineralization.
The holes intersected an extensive
zone of Cu-Au-Ag mineralization
(with Zn and Pd credits), with better
intersections including 47m @ 5.3%
Cu, 26 m @ 3.2% Cu, 75 m @ 2.4% Cu,
and 22 m @ 4.9% Cu. Resource definition
drilling is underway, as are airborne,
ground, and downhole EM surveys
as the mineralization is strongly
conductive.
In order to attract exploration to the
more remote regions of Australia, the
state and federal agencies are systematically
collecting regional geologic, geochemical,
and geophysical datasets,
and releasing these to explorers at minimal
cost. One winner from this wise
investment has been Meteoric
Resources. The company has secured
priority right of application to a regional
10 ´ 8 km gold-in-soil anomaly which
was identified by a helicopter-supported
regional geochemical sampling program
carried out by Geological Survey of WA
following field work by Geoscience
Australia which highlighted the coppergold
and gold potential of the Mt Webb
area in the western part of the Arunta
Complex. The Arunta Complex extends
across the WA/NT border and comprises
an extensive sequence of Proterozoic
metamorphic rocks intruded by granites.
The main anomaly is based on
regolith samples taken on a grid cell of
5 × 2.5 km equating to one sample per
12.5 km2 . This wide-spaced sampling
has defined a coherent gold anomaly
with gold-in-soil values ranging from
10 to 20 times background (1 ppb Au)
and one lag sample (surficial rock
float) containing 0.4g/t Au. The gold
anomaly is supported by anomalies in
a range of other elements.
Integra Mining has reported further
high-grade intersections from diamond
drilling at its Salt Creek gold deposit,
forming part of its Randalls gold project
located 60 km east of Kalgoorlie,
adjoining the Trans Australian Railway.
Recent intersections have included 40.5
m @ 6.48 g/t Au and 15.5 m @ 4.51 g/t
Au. The feasibility study for the Randalls
project is expected to be completed
midyear, based on a resource of 1.8 M
oz Au at a grade of 2.8 g/t Au.
A step-out drill hole at Mincor
Resources’ Mariners nickel mine
assayed 35 m @ 7.0% Ni (true width 6.4
m) located 180 m beyond the currently
known limits of mineralization and
suggesting the potential for new ore
shoots.
NORTHERN TERRITORY
Emmerson Resources’ exploration
efforts in the Tennant Creek goldfield
have been boosted by the entry of
Ivanhoe Australia as a shareholder in
the company and also as a joint-venture
partner in all of Emmerson’s tenements
in the district. Tennant Creek is one of
the richest and largest Proterozoic goldfields
in Australia with historical production
of more than 5.5 Moz of highgrade
gold and approximately 488 kt of
copper.
NEW ZEALAND
Perth-based Western Media Holdings
launched www.nzresources.com, which
features news about mineral and
energy resources in New Zealand. They
also published The Mineral Resources of
New Zealand 2009, a CD-ROM containing
information on mines, prospects
and companies. It is available from
them, or in the New Zealand Minerals
Information Pack offered by Crown
Minerals, see www.crownminerals.govt.
nz/cms/minerals/publications/publica
tions#NZinfopack.
In the Hauraki goldfield, Newmont
has continued drilling near-mine epithermal
gold prospects adjoining their
Waihi gold mine and have also initiated
reconnaissance diamond drilling
on Glass Earth Gold permits approximately
15 km to the north of Waihi.
Encouraged by the recent high gold
price, Newmont is investigating both an
eastern extension to the Martha open
pit and underground mining of the
Gladstone zone from a drive extension
from the Favona underground mine.
At Oceana Gold’s Macraes orogenic
gold mine in Otago, 34 drill holes were
completed to test the northeastern
extension of the Coronation deposit,