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
two
known high-grade occurrences of BIF-hosted iron at Mt Ida, similar
to that supporting Portman.
BIF
occurrences are large, 7km x 3km and 4km x 2km respectively
Surface
sampling results include 66.64% iron with supporting low phosphorus
and significant target tonnage available above the level of
the surrounding plain
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.
Mt Ida – portion of 7km exposure of iron ore bearing
rocks (click to enlarge)
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 - Mt Ida
The Mt Ida iron project is located 80km northwest of Menzies
in the central Yilgarn region of Western Australia and lies
in the Ularring greenstone belt. It comprises an EL application
numbered E29/560 that covers an area of 175km2. Access from
Kalgoorlie is via the sealed Wiluna Road to Menzies then by
the formed Menzies-Sandstone road that traverses the southern
parts of the tenement. Access within the project area is via
pastoral and survey station tracks. Regional infrastructure
is good, with formed roads from Mt Ida to Menzies, then rail
spur lines at Menzies for ore transport to Esperance.
The Mt Ida tenement includes two known, large, high-grade occurrences
of BIF- hosted iron similar to that supporting the Koolyanobbing
Iron Ore operations of Portman. The two occurrences are known
as Mt Ida and Mt Mason and cover 7km x 3km and 4km x 2km respectively
within an undulating line of hills up to 100m above the level
of the surrounding plain. The large size of the BIF occurrences
is highlighted by regional aeromagnetic data which shows significant
magnetic highs at the Mt Ida and Mt Mason prospects.
BIF at the Mt Ida occurrence has been subject to intense folding
and has been partially obscured by laterite. Its western margin
is defined by almost vertical cliffs that drop approximately
70m to a granite plain below. Dip is approximately 45° to
the west. The Mt Mason occurrence lies 12km northwest with sub-parallel
BIF horizons forming a prominent ridge, dip is moderate to the
west.
Geology
and Mineralisation
BIF at the Mt Ida occurrence has been subject to intense folding
and has been partially obscured by laterite. Its western margin
is defined by almost vertical cliffs that drop approximately
70m to a granite plain below. Dip is approximately 45° to
the west. The Mt Mason occurrence lies 12km northwest with sub-parallel
BIF horizons forming a prominent ridge, dip is moderate to the
west.
Mt Ida is an obvious target for a modern exploration. Historical
results from government sampling demonstrate mineralisation
of an economic tenor combined with ample strike lengths (4km
and 7km) of BIF. Surface sampling results include 66.64% iron
with supporting low phosphorus (0.05%) and significant target
tonnage is available above the level of the surrounding plain.
Regional infrastructure is good, with formed roads from Mt Ida
to Menzies, then rail spur lines at Menzies for deli of ore
to deepwater loading facilities at Esperance.
History
The BIF hosted iron accumulations of Mt Ida and Mt Mason were
noted by government geologists as early as 1901, however it
was over 10 years later that the first prospecting work commenced.
In 1912, the Geological Survey of Western Australia (“GSWA”)
published brief descriptions of the iron ore accumulations,
with results of limited surface sampling up to 96.98% Fe2O3.
In 1959, surface sampling at Mt Mason outlined a high-grade
lens of hematite of 66.64% iron and 0.05% phosphorus.
Further sporadic sampling was carried out at Mt Mason in 1970
by private prospectors. Results of sampling in the west of the
tenement returned between 54.6% iron and 65.8% iron. Results
justified follow-up efforts but none were carried out.
No systematic exploration activities for iron ore have been
carried out within the Mt Ida tenement despite the large strike
extent of BIF and encouraging results from early work.
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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