Irvine Island
Encyclopedia
Irvine Island is located off the Kimberley coast of Western Australia
in the Buccaneer Archipelago
. It is about 250 km north-east of Broome
, 140 km north of Derby
and hosts an unmined deposit of iron ore. Irvine Island has a surface area of approximately 9 square kilometers and is situated 5 km west of Cockatoo Island
.
and Cockatoo
have been in productive mining for over 50 years.
Iron mineralisation at the Hub is much younger than the deposits of the Pilbara and is contained within sedimentary rocks as visible dark brown bands within the otherwise pale brown and generally repetitive sandstones. However, one layer in particular, the Yampi Member, contains very high concentrations of iron and has been the primary focus of exploration and mining activity in the region. This layer outcrops on all three islands of the Hub making it the closest iron ore deposit in Australia to Asia.
The Yampi Member is a ferruginous clastic sedimentary rock and constitutes the upper part of the Pentecost Sandstone. On Irvine, it unconformably
overlies the Elgee Siltstone and is characterised primarily by dark grey haematite and magnetite
quartz sandstone
and quartz pebble conglomerate
.
), explored for iron on Koolan
, Cockatoo
and Irvine Islands from the early 20th century. Three mineral claims and two mining leases were granted to AIS on Irvine Island in the mid 1930's and early 1950s.
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
in the Buccaneer Archipelago
Buccaneer Archipelago
The Buccaneer Archipelago is a group of islands off the coast of Western Australia near the town of Derby in the Kimberley region. The closest inhabited place is Bardi located about from the western end of the island group....
. It is about 250 km north-east of Broome
Broome, Western Australia
Broome is a pearling and tourist town in the Kimberley region of Western Australia, north of Perth. The year round population is approximately 14,436, growing to more than 45,000 per month during the tourist season...
, 140 km north of Derby
Derby, Western Australia
Derby is a town in the Kimberley region of Western Australia. At the 2006 census, Derby had a population of 3,093. Along with Broome and Kununurra, it is one of only three towns in the Kimberley to have a population over 2,000...
and hosts an unmined deposit of iron ore. Irvine Island has a surface area of approximately 9 square kilometers and is situated 5 km west of Cockatoo Island
Cockatoo Island (Western Australia)
Cockatoo Island is an island in the Buccaneer Archipelago off the coast of Western Australia near the town of Broome.Iron ore mining began at Cockatoo Island in 1951. BHP operated the mine in the early 1950s and ran it as a complete town site until 1984 when the ore body had been mined to sea level...
.
Geology and mineralisation
Irvine Island is one of three Islands forming the Kimberley Iron Ore Hub. The other two islands, KoolanKoolan Island
Koolan Island is an island off the Kimberley coast of Western Australia in the Buccaneer Archipelago. It is about 1,900 km north of Perth, and about 130 km north of Derby...
and Cockatoo
Cockatoo Island (Western Australia)
Cockatoo Island is an island in the Buccaneer Archipelago off the coast of Western Australia near the town of Broome.Iron ore mining began at Cockatoo Island in 1951. BHP operated the mine in the early 1950s and ran it as a complete town site until 1984 when the ore body had been mined to sea level...
have been in productive mining for over 50 years.
Iron mineralisation at the Hub is much younger than the deposits of the Pilbara and is contained within sedimentary rocks as visible dark brown bands within the otherwise pale brown and generally repetitive sandstones. However, one layer in particular, the Yampi Member, contains very high concentrations of iron and has been the primary focus of exploration and mining activity in the region. This layer outcrops on all three islands of the Hub making it the closest iron ore deposit in Australia to Asia.
The Yampi Member is a ferruginous clastic sedimentary rock and constitutes the upper part of the Pentecost Sandstone. On Irvine, it unconformably
Unconformity
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe...
overlies the Elgee Siltstone and is characterised primarily by dark grey haematite and magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
quartz sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
and quartz pebble conglomerate
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
.
Historical exploration
Australian Iron and Steel, later BHP (now BHP BillitonBHP Billiton
BHP Billiton is a global mining, oil and gas company headquartered in Melbourne, Australia and with a major management office in London, United Kingdom...
), explored for iron on Koolan
Koolan Island
Koolan Island is an island off the Kimberley coast of Western Australia in the Buccaneer Archipelago. It is about 1,900 km north of Perth, and about 130 km north of Derby...
, Cockatoo
Cockatoo Island (Western Australia)
Cockatoo Island is an island in the Buccaneer Archipelago off the coast of Western Australia near the town of Broome.Iron ore mining began at Cockatoo Island in 1951. BHP operated the mine in the early 1950s and ran it as a complete town site until 1984 when the ore body had been mined to sea level...
and Irvine Islands from the early 20th century. Three mineral claims and two mining leases were granted to AIS on Irvine Island in the mid 1930's and early 1950s.