Iron ore and gold, Eastern Goldfields, Central Yilgarn
Project
Summary
 Strong
demand from Chinese steel industry
Australia
one of two main suppliers of exported iron ore with high grade
product
Established
production from BIF in the Central Yilgarn near Red Rock’s
tenements by Portman Mining
Good
infrastructure
Takeover
of Portman Mining by Cleveland Cliffs Inc and plans for increased
production
Outcrop
of BIF is prevalent in the north of the tenement
BIF
horizons range in thickness from 5m to 60m
Surface
sampling has confirmed hematite and goethite presence
General
- Area
The Central Yilgarn Iron project comprises three ELAs being
E29/560 Mt Ida, E29/581 Mt Alfred and E30/296 Mt Hope, collectively
covering approximately 460km2. Banded Iron Formation (“BIF”)
strike-length is significant within each of the tenements.
Results of previous surface sampling at Mt Ida include economic
grades of hematite and goethite iron ore with supporting low
phosphorus. The tenements are located in a region with good
infrastructure and existing iron ore production from the Koolyanobbing
operations of Portman Ltd.
Access to each of the tenements is good with sealed and formed
gravel roads directly linking the regional centre of Kalgoorlie
with each project area. A spur line at nearby Menzies provides
a rail link to deepwater port facilities at Esperance.
Exploration for gold, copper, uranium and nickel has been
carried out in the Central Yilgarn area. However no systematic,
modern efforts for iron ore have been carried out within the
current tenements despite these areas showing demonstrated
prospectivity for this commodity.
Geology
The tenements are in the central parts of the Yilgarn Craton
in Western Australia. The Yilgarn block is a segment of stable
Archaean crust composed of typical greenstone belts of volcanic,
sedimentary, and intrusive sequences interspersed between
large areas of granitic lithologies. The Yilgarn is well endowed
in commodities such as gold, nickel, copper, and iron. Major
gold camps include Kalgoorlie, Southern Cross, Leonora, Meekatharra
and Wiluna. Nickel production is sourced from the Mt Keith,
Kambalda, Lake Johnston, Forrestania and Ravensthorpe areas.
Iron production in the Yilgarn is predominantly from the Koolyanobbing
area in the Central Yilgarn, with smaller operations in the
Northwest Yilgarn that include Tallering Peak.
Tenements of the Central Yilgarn Iron project cover parts
of the generally north- striking Ularring and adjacent Illaara
Greenstone Belts. These belts comprise basalt, intrusive ultramafic
units, acid volcanics, interlayered clastic sediments, and
BIF bounded by granite to the east and west. Significant structural
deformation has resulted in regional scale folding, strong
foliation, medium-high metamorphic grades and thrust-repetition
of stratigraphy. Importantly, metamorphism and deformation
has altered original magnetite mineralisation in the BIF units
to hematite and goethite with a corresponding increase in
grade up to 67% Fe.
Koolyanobbing
Iron Operation
Koolyanobbing Iron is owned and operated by Portman Ltd (“Portman”),
which is a subsidiary of US based Cleveland Cliffs Inc. The
operation is located approximately 150km southwest of the
Mt Ida, Mt Alfred and Mt Hope tenements, and 175km west of
Kalgoorlie. It currently produces some 5,000,000 tpa of ore
that is shipped to Asian markets via the port of Esperance.
Ore feed for the primary crushing facilities at Koolyanobbing
has historically been sourced from deposits at Koolyanobbing,
but more recently been supplemented with ore trucked from
resources at Windarling and Mt Jackson, 100km north. An expansion
of infrastructure from 5,000,000 tpa to 8,000,000 tpa is currently
underway.
Deposits at Koolyanobbing were first mined in 1948 by the
Western Australian Government to supply the charcoal iron
industry at Wundowie near Perth. Further deposits were developed
in the mid 1960s by BHP Ltd, who operated the mine until 1983.
Portman resumed mining in 1994 under a Joint Venture agreement
with the Anshan Iron and Steel Complex of China. In 2000 Portman
took 100% ownership and looked toward expanding the Koolyanobbing
operation with increased ore feed from satellite ore-bodies
at Mt Jackson and Windarling.
Iron ore is sourced from BIF hosted ore-bodies in greenstone
sequences; a similar geological setting to that at the Mt
Ida, Mt Alfred, and Mt Hope areas. The primary iron formation,
which has been strongly folded and thickened, is composed
of banded magnetite-talc schist and quartz-magnetite containing
some pyrite, and siderite and massive pyrite containing some
specular hematite, magnetite and graphite.
The original Dowd's Hill deposit at Koolyanobbing had a strike
length of 900 m, varied from 50m to 300m in width, and extended
for 50m to 80m below the current ground level. The ore comprised
hard, massive goethite, coarse grained, friable specular hematite,
some massive fine grained hematite, yellow limonite, and minor
magnetite. Bands of chlorite schist and friable iron-leached
jaspilite also occur within the ore zones. The average grade
of the ore between 1967 to 1972 when 8Mt was mined was 61.4%
Fe, 0.13% P with 6% LOI. In 2004, global resources (Inferred,
Indicated and Measured) of goethite and hematite ore for the
Koolyanobbing, Mt Jackson and Windarling ore-bodies was 149.5Mt
at 62.13% iron, 0.11% phosphorus and 6.71% LOI.
General - Mount
Hope
The Mt Hope tenement is located 60km east of Menzies and 150km
northwest of Kalgoorlie in the central Yilgarn of Western
Australia, covering an area of 75km2. Access to Mt Hope from
Kalgoorlie is via the sealed Wiluna Road to Menzies then the
formed Evanston-Menzies Road that passes across the south
of tenement. Pastoral tracks provide reasonable access within
the tenement.
Geology
and Mineralisation
As at Mt Ida, the Mt Hope tenement covers rocks of the Ularring
greenstone belt that comprise generally north striking interlayered
metamorphosed basalt, felsic volcanic, sedimentary and BIF
units, with lesser intrusive ultramafic units. Rocks within
the tenement form a 12km long, northwesterly striking spur
off the main belt that dips moderately west.
Outcrop of BIF is prevalent in the north of the tenement,
but relief is subtle when compared to the 90-100m peaks at
Mt Alfred and Mt Ida. Flanking lithologies are largely covered
by colluvium with only minor subcrop of basalt and sedimentary
rocks. BIF horizons range in thickness from 5m to 60m and
tight folding is evident. Hematite and goethite mineralisation
has been observed but no analytical data including iron is
recorded.
Mt Hope is located 60km west of Menzies, and 40km south of
Mt Ida. It contains significant BIF strike length of up to
12km, confirmed by detailed aeromagnetic interpretation and
field work. Surface sampling has confirmed hematite and goethite
mineralisation is present, and evaluation of grade and tonnage,
by modern exploration methods, is warranted.
History
Between 1987 and 1989 gold exploration was carried out over
the tenement by the Carpentaria Exploration Company Pty Ltd
following interpretation of regional aeromagnetics. The intense,
discontinuous magnetic high in the centre of the Mt Hope tenement
was confirmed to be caused by a remnant BIF horizon. Follow-up
work included stream sediment sampling, rock-chip sampling
and RAB drilling. However, as with Mt Alfred, no analysis
included iron.
Stockdale Exploration Ltd carried out exploration for diamonds
over the Mt Hope tenement between 1994 and 1995. Work included
a detailed aeromagnetic survey, stream sediment sampling,
loam sampling and RC drilling. Chrome spinels were recovered
from stream sediment sampling of nine aeromagnetic anomalies.
However, the spinels were considered to be derived from unrelated
ultramafic rocks with no kimberlitic affinities. Drilling
returned negative results for kimberlites. The magnetic anomalies
were attributed to mafic-rich granite, banded iron-formation
and gabbro. No analysis for iron was carried out.
In summary, as with Mt Alfred, exploration has taken place
over the Mt Hope tenement but none specifically for iron ore.
This is despite the confirmation of hematite and goethite
mineralisation in the BIF, and its reasonable strike extent.
Based on an independent geological assessment of the Australian
Manganese and Iron Projects located in the States of Western
Australia and Tasmania, Australia by Al Maynard and Associates.
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