PorterGeo
SEARCH  GO BACK  SUMMARY  REFERENCES
Scotia

Western Australia, WA, Australia

Main commodities: Ni Cu
Our International
Study Tour Series
The last tour was
OzGold 2019
Our Global Perspective
Series books include:
Click Here
Super Porphyry Cu and Au

Click Here
IOCG Deposits - 70 papers
All available as eBOOKS
Remaining HARD COPIES on
sale. No hard copy book more than  AUD $44.00 (incl. GST)
Big discount all books !!!


Scotia was a small komatiite hosted massive sulphide Fe-Ni-Cu deposit located some 65 km north of Kalgoorlie in Western Australia.

The deposit was discovered in 1968 and mined from October 1969 until cessation of operations in September 1977 due to a major underground collapse.

The Scotia deposit is hosted by mafic and ultramafic rocks that are part of a continuous belt striking NNW from Kalgoorlie and Kambalda. These greenstones, which belong to the 2715 to 2690 Ma Kambalda Sequence, are typically tightly folded with NNW axes and are metamorphosed to lower greenschist facies. The orebody and host sequence dips steeply west and it is considered to form the Eastern limb of a south plunging syncline. Granite outcrops in the core of the adjacent anticline immediately to the east.

The succession in the deposit area comprises a lower low-Mg tholeiitic basaltic unit that is ~500 m thick, with intercalated tuffs, thin sedimentary rocks and some pods of high Mg basalt and gabbro. The basalts comprise ~65% amphibole (either hornblende or actinolite); 20% plagioclase; 10% quartz, 3% chlorite and 2% opaques. Approximately 5 to 15 m of black graphitic slates with minor pyrite and quartz-biotite schists separate the basalts from the overlying ultramafic suite. The schists are interpreted to be of epiclastic volcano-sediments with an andesitic composition. The ultramafic suite is up to 600 m thick and comprises numerous discrete lenses of peridotitic rock intercalated with thin discontinuous lenses of metasedimentary rocks. The ultramafic rocks are composed of olivine, serpentine (replacing olivine) amphibole, chlorite and minor calcite and host the mineralisation. The ultramafics are overlain by a further 600 m of sedimentary rocks.

In the immediate deposit area, the sedimentary unit is separated from the lower sections of the ultramafic by a chlorite shear zone up to 15 cm thick. Adjacent to be contact with the overlying ultramafic rocks, the sedimentary unit has been bleached and silicified in many places. The ore bearing ultramafic is a single lens-shaped dunitic/komatiite unit ~500 m long and up to 50 m wide that extends from the surface to a depth of at least 450 m and occurs at the base of the ultramafic suite. It strikes NNW and dips steeply west. The orebody occurs in its central sections, in an embayment of its footwall into the underlying sedimentary rocks, and has a strike length of 150 m, thickness of up to 20 m and down plunge extent of 370 m.

The sulphide orebody comprises a basal massive sulphide, progressively overlain by network and disseminated sulphides and then a barren zone, which is, in turn followed by an altered zone and the overlying ultramafic suite. The upper alteration zone ranges from a few cm to 5 m thick and occurs in highly metamorphosed and metasomatised sedimentary rocks and mafic volcanics. The orebody contains ~10% sulphides and has an estimated average grade of 3.07% Ni, 0.25% Cu at a cut-off of 1% Ni. The discontinuous basal massive sulphides, where present, are up to 2 m thick and contain 15 to 20% Ni, whilst the overlying up to 20 m of network and disseminated ore carries 1 to 7% Ni. The ore contains pentlandite, violarite, pyrrhotite, pyrite and minor valeriite, chalcopyrite, magnetite and Cr spinel. The present sulphide mineralisation is not the original, and was released during the serpentinisation of the olivine. The serpentinised host has well preserved olivine crystals at its core, with inclusions of pentlandite and magnetite.

Production to 1977 was 1.4 Mt @ 2.2% Ni.
Remaining reserves in 1981 were 0.82 Mt @ 2.14% Ni.

For more detail see the reference(s) listed below.

The most recent source geological information used to prepare this summary was dated: 1981.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


  References & Additional Information
   Selected References:
Christie D  1975 - Scotia Nickel Sulphide deposit: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne   Mono 5 pp 121-125
Marston, R.J., Groves, D.I., Hudson, D.R. and Ross, J.R.,  1981 - Nickel sulfide deposits in Western Australia: a review: in    Econ. Geol.   v.76, pp. 1330-1363.
Page M L, Schmulian M L  1981 - The proximal volcanic environment of the Scotia nickel deposit: in    Econ. Geol.   v76 pp1469-1479
Stolz G W, Nesbitt R W  1981 - The Komatiite nickel sulfide association at Scotia: a petrochemical investigation of the ore environment: in    Econ. Geol.   v76 pp 1480-1502


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

Top | Search Again | PGC Home | Terms & Conditions

PGC Logo
Porter GeoConsultancy Pty Ltd
 International Study Tours
     Tour photo albums
 Ore deposit database
 Conferences & publications
 Experience
PGC Publishing
 Our books  &  bookshop
     Iron oxide copper-gold series
     Super-porphyry series
     Porhyry & Hydrothermal Cu-Au
 Ore deposit literature
 
 Contact  
 What's new
 Site map
 FacebookLinkedin