Windarra Ni Mine (Mount Windarra; Windarra; Discovery gossan; Poseidon deposit), Laverton, Laverton Shire, Western Australia, Australiai

Regional Level Types
Windarra Ni Mine (Mount Windarra; Windarra; Discovery gossan; Poseidon deposit)	Deposit
Laverton	- not defined -
Laverton Shire	Shire
Western Australia	State
Australia	Country

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In the late 1960's there was a shortage of nickel worldwide. Exploration work at the time, led to the discovery of massive nickel deposits in Western Australia. In April 1969, Ken Shirley employed by Poseiden Exploration, was drilling just south of Mt Windarra, 15 kilometres north-west of Laverton. He intersected rock containing 3.56% nickel and 0.55% copper. There was a rush on Poseiden shares which rocketed from 0.80c to $280 a share in five months. By 1976 they had fallen to 0.38c.

The mine operated from 1974 to 1994, both as an open pit and underground operations to 550 metres depth, initially by Poseidon until it went into receivership in 1976, then by Western Mining Corporation. The mine closed in the first instance in 1978, due to sustained low nickel prices, the partial collapse of an underground pillar, and failure of a massive blast programme.

In 2005, Niagara Mining Ltd purchased the mine from Western Mining and began re-furbishing the old mine. Poseidon Nickel Limited continued work to un-water and develop the mine from 2011, with the intention to re-open the underground workings. This includes an underground crushing station at the 450 metre level with a shaft hauling ore to the surface. Mount Windarra contains a resource of 498 000 tonnes of ore at 1.78 Ni grade yielding 9000 Ni tonnes.

In the early 1970's , glaukosphaerite was noted at the mine as thin veinlets in goethite-quartz-chalcedony rock.

The sequence of units at Mount Windarra are as follows:
1. Corridor Ultramafics at 3 to 45 metres thick of unmineralised ultramafic in the mine area and a short distance to the south. It consists of metamorphosed talc-chlorite-dolomite assemblage.

2. Banded Iron Formation 1 to 15 metres thick of banded sulphidic chert (quartz-pyrite), and feldspathic quartzite.

3. Ultramafic sequence 100 to 300 metres thick of differentiated ultamafic flows, overlain by magnesian and thin tholeiitic basalt. Away from the mine area, the sequence is dominated by tremolite-chlorite-talc metamorphic picritic flows, and localised thin peridotite flows, at or close to the basal contact.

4. Basal olivine peridotite flows capped by thin picritic flow tops 1 to 2 metres thick, showing a complete sequence of textures.

5. Ultramafic flow which hosts the B shoot on the south side of the AB drag fold, overlain by the mineralised E,C,D,G shoot flows, the overlapping A shoot (referred to as A Hanging Wall), and E shoot flow in direct contact with the banded iron formation to the north of the A flow shoot.

(F Shoot was removed as a listing name as it refers to one of several shoots in the mine rather than an alternative name for the whole mine). There are seven distinct south plunging shoots named A to G, separated by two overlapping flows, each containing iron-nickel-copper sulphide mineralisation. The ore shoots are 2 to 20 metres thick, 50 to 250 metres long, and down dip extends up to 900 metres.

A Shoot has an Inferred resource of 85 000 tonnes of ore at 2.19 Ni grade for 2000 Ni tonnes; B Shoot Inferred 69 000 tonnes of ore at 1.52 Ni grade for 1000 Ni tonnes; C Deeps Indicated 434 000 tonnes of ore at 1.75 Ni grade for 7 500 Ni tonnes, and Inferred 1 515 000 tonnes of ore at 1.9 Ni grade for 29 000 Ni tonnes; D Deeps Inferred 547 000 tonnes of ore at 1.37 Ni grade for 7 500 Ni tonnes; G Deeps Inferred 1 063 000 tonnes of ore at 1.46 Ni grade for 15 500 Ni tonnes; G Shoot Upper Indicated 282 000 tonnes of ore at 1.29 Ni grade for 3 500 Ni tonnes and Inferred 31 000 tonnes of ore at 1.22 Ni grade for 500 Ni tonnes; F Shoot Indicated 178 000 tonnes of ore at 1.50 Ni grade for 2 500 Ni tonnes and Inferred 126 000 tonnes of ore at 1.56 Ni grade for 2000 Ni tonnes; and H Shoot Indicated 28 000 tonnes of ore at 1.87 Ni grade for 500 Ni tonnes. (All 0.90% cut off grade)

D shoot is the largest, and with A and B shoots historically formed 80% of the ore mined. The Hanging Wall at the mine is strongly foliated amphibolite. A series of steep south plunging dextral drag folds deform the stratigraphy and also control the distribution of the ore shoots.

Mineralisation is found at the base of the olivine cumulate ultramafic sequence. Massive sulphide is the dominant ore type, and non massive sulphide contain matrix textured (25-40% sulphide), disseminated (5-25% sulphide) and blebby (20%-30% sulphide). The primary ore contains pyrrhotite, pentlandite, pyrite and chalcopyrite in that order of abundance. Nickel to copper ratio averaged 9:1, but can be 4:1 in the copper rich basal matrix.

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Mineral List

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33 valid minerals.

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