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Otway Ni deposit, Nullagine, East Pilbara Shire, Western Australia, Australia

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Latitude & Longitude (WGS84): 21° 44' 9'' South , 120° 4' 40'' East
Latitude & Longitude (decimal): -21.73611,120.07778
GeoHash:G#: qsjkk7jcz
Locality type:Deposit
Köppen climate type:BWh : Hot deserts climate

Ni mineralization occurring in shears in Archean serpentinized peridotite near Nullagine. The bulk of the mineralization is attributed to the effects of hydrothermal and/or metasomatic activity along shears in the serpentine. The late veinlets of Ni minerals and the replacement of millerite and polydymite are attributed to supergene effects.

Located 23 km north of Nullagine. Discovered sometime around 1977 by prospector and miner, Charles Albert Otway, from Gosnells (Perth), Western Australia. He allowed the CSIRO access to study the mineral species it contained.

It is the type locality from nullaginite, otwayite, and paraotwayite.

Nullaginite is found at only three locations worldwide. It is crystallographically similar to rosasite and glaukosphaerite. Nullaginite at Otway occurs as ovoid to irregular nodules up to 2mm, and cross-fibre veinlets, with a dull lustre in nodules and silky lustre in veinlets.

Otwayite is found at the location in narrow veinlets 0.5-1mm, and represents a late stage fracture filling, and transects nickeloan serpentine, millerite, polydymite, and apatite. Also associated with otwayite in the veinlets are magnesite, gaspéite, and pecoraite. Otwayite has a fibrous habit, usually rosette-like aggregates. It is unique with no close mineral group or other species with a similar chemical composition.

It is impossible to distinguish between otwayite and paraotwayite from the Otway Prospect, visually in hand specimens. Under SEM paraotwayite shows a net-like pattern with a porous texture. Otwayite contains predominantly carbonate with some sulphate, and paraotwayite sulphate with some carbonate, suggesting a paragenetic relationship between the two in which carbonate is replaced by sulphate. Like otwayite, paraotwayite forms fibres to 0.5mm in length, often intergrown forming net-like masses or rosettes. The species is found only at the Otway Prospect, and a Chilean meteorite. All three type locality species are bright green.

The principal nickel minerals found at Otway are millerite, polydymite, and pecoraite, which occur as nodular grain concentrations 1-5mm in diameter. Polydymite is replaced by millerite, which in turn is replaced by gaspéite. Other minerals in the shears include various types of serpentine and magnesite, coarse chlorite, and apatite. This assemblage is cut by late veinlets of gaspéite, pecoraite, otwayite, and nullaginite. There are also trace amounts of barite, cinnabar, parkerite, shandite, breithauptite, and nickeloan greenockite. The majority of mineralisation is attributed to the effects of hydrothermal and/or metasomatic activity along the shears in serpentine. However, concretionary magnesite in some of the shears is the result of Tertiary weathering. Late veinlets of nickel mineralisation, and the replacement of millerite with polydymite are from supergene effects.

The Mindat co-ordinates are where maps confirm the location to be, however, only possible very minor workings can be seen where mineral specimens have come from in the past (likely late 1970's). The deposit appears to be small, and/or never explored to any great extent after its initial discovery beyond from a scientific standpoint.

Mineral List

21 valid minerals. 3 (TL) - type locality of valid minerals.

Rock Types Recorded

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Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

2500 - 2800 Ma

ID: 734220
Hardey Formation

Age: Neoarchean (2500 - 2800 Ma)

Stratigraphic Name: Hardey Formation

Description: Sandstone, siltstone, shale, lithic wacke, mudstone, arkose, calcareous beds, conglomerate; porphyry, porphyry breccia; quartzite; dacitic to rhyolitic lavas; quartz-feldspar-mica schist; boulder breccia; basalt; felsic pyroclastics, ultramafic lava.

Comments: sedimentary; igneous volcanic; synthesis of multiple published descriptions

Lithology: Sedimentary; igneous volcanic

Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia). [5]

3200 - 3600 Ma

ID: 3191854
Archean volcanic rocks

Age: Paleoarchean (3200 - 3600 Ma)

Comments: Pilbara Craton

Lithology: Mafic-ultramafic volcanic rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Nickel, E.H., Hallberg, J.A., and Halligan, R. (1979) Unusual Nickel Mineralization at Nullagine, Western Australia. Journal of the Geological Society of Australia: 26: 61-71.
Nickel, E.H. and Graham, J. (1987) Paraotwayite. A new nickel hydroxide mineral from Western Australia. Canadian Mineralogist: 25: 409-411.
Marston, R.J. (1984) Nickel Mineralisation in Western Australia. Geological Survey of Western Australia.
Nickel, E.H., Robinson, B.W., Davis, C.E.S., and Macdonald, R.D. (1977) Otwayite- a new nickel mineral from Western Australia. American Mineralogist: 62: 999-1002.
Nickel, E.H. and Barry, L.G. (1982) New Mineral names: 67: 854-860 [Nullaginite].
Nickel, E.H. (1973) An Occurrence of Gaspeite and Pecoraite in the Nullagine Region of Western Australia. Mineralogical Magazine: 39: 113-115.

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