Kambalda, Coolgardie Shire, Western Australia, Australiai

Regional Level Types
Kambalda	Town
Coolgardie Shire	Shire
Western Australia	State
Australia	Country

Kambalda is a mining district. The town of Kambalda was first established as a gold mining town in 1897, and remained so until 1966. Nickel was then found here and the town now revolves primarily around nickel mining.

The town itself is essentially split in two: Kambalda East and Kambalda West.

The deposit was discovered 1966 and mining commenced 1967. Owned by Western Mining. In 1986 this deposit was estimated to contain 7% of the western world's nickel reserves. Ore body contains the Lunnon shoot and the Durkin shoot (Durkin shaft).

Nickel is the 1960's was a rare commodity. In the late 1960's to early 70's, massive nickel deposits were discovered in Western Australia. It is known in Western Australian history as the Nickel Boom. Australia holds 35% of world reserves, and 90% of this is in Western Australia. Most of the nickel deposits were discovered in the Eastern Goldfields province, particularly centred on the Kambalda region. At present (2012) 22 nickel mines are operational in the Kambalda area. Western Mining Corporation discovered nickel at Kambalda in 1965, and the first mine (Silver Lake Mine) opened in 1966. The Kambalda region produces 35 000 tonnes of nickel metal pa.

Specimens generally come from the 132 North Mine near Widgiemooltha, and the Otter Shoot Mine on the outskirts of the East Kambalda townsite. Nickel secondary species from Kambalda mines are described by geologists as rare. It needs to be said mining companyie often simply describe the whole lot as nickel ore, which gets processed regardless of the composition.

Geology speaking, the Kambalda Dome nickel mineralisation is one of the most heavily studied in Western Australia. A detailed description is beyond the scope (and my brain power) of this summary.

The Kambalda Dome shows as an elogated feature in a north north-west direction, and located 56 kilometres south south-east of Kalgoorlie.

From the lowest upwards, is the Lunnon Basalt, overlain by the Kambalda Komatiite which hosts the nickel sulphide mineralisation, Devons Consol Basalt, then a package of slates and greywackes.

The Kambalda Komatiite lays between the two basalt members. Nickel sulphide mineralisation is concentrated at its contact with the Lunnon Basalt, where it occupies the base of the lava flow, in incised channels forming elongated lenses and ribbon like structures. These trend in a north north-west direction, up to 3 kilometres long and 300m wide. The channel flows themselves can be up to 100m thick, 500m wide, and 15 kilometres in length. It contains pyrrhotite-pentlandite-pyrite-chalcopyrite, with locally abundant millerite.

The sulphides in the komatiite lava flows are denser, so tend to pool in topographic low areas, enhanced by the thermal erosion of the substrate by the lava.

The ore zone in the Kambalda Komatiite from the base upwards consists of a zone of massive sulphides (95% sulphide) of metasedimentary or melted material and enclaves of olivine. Overlaying this is a zone of matrix sulphide of a jackstraw texture, composed of bladed to acicular metamorphic olivine, spinifex textured in a matrix of nickel sulphide. Next a zone of net textured ore, rarely observed, but assumed, as nickel sulphide forming a network textured groundmass liquid in which olivine crystals float in massive sulphide. Described as having the consistency of toothpaste, we are uncertain though it does much to fight tooth decay. Lastly a disseminated sulphide zone grading upwards to barren ultramafic in a fine grained groundmass.

There is a variation in deposits with some zones missing. While originally formed as generally horizontal volcanic lava flows, processes since such as metamorphism, folding etc create a large degree of variability between the deposits.

The oxidised weathered zone above the ore, is dominated by boxworks of goethite, hematite, magherite and ocher clays. Non sulphide nickel mineralisation is usually soluable, and preserved as carbonates, or within the ore as nickeline. Mineral species such as gaspeite, hellyerite, otwayite, widgiemoolthalite, and related nickel carbonates have been preserved by the arid environment, but are still rare. Secondary copper species malachite, azurite, chalcocite, and cobalt-nickel compounds are more persistent in the boxworks.

The oxidised zone includes goethite, hematite, limonite, often associated with polydymite and violarite, supergene in origin in the lower portions of the saprolite rock.
Located about 25 km NNE of Widgiemooltha.

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