Digger Rocks (South Endeavour), Kondinin Shire, Western Australia, Australia

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Located 82 km east south east of Hyden and 5 km south east of South Ironcap Hill.

The Forrestania Region is found just beyond the eastern limits of the Wheatbelt. The area is heathland, with salmon gum woodland in low lying areas. The region contains no towns.

Several nickel deposits occur here, controlled by a company called Western Areas NL. They obtained leases for the area in 1993. The Flying Fox Mine opened in 2008, followed by the Spotted Quoll Mine, and construction of a nickel concentration plant in 2010. Three more mines are planned, including Digger Rocks South, although no activity could be seen when visited in 2011. Major mineralisation also occurs at Cosmic Boy and New Morning, with several other prospects including Liquid Acrobat, Mt Hope, Beautiful Sunday, Carr Boyd, Seagull and Rat Rat (I kid you not).

Digger Rocks is an abandoned open pit, with waste rock piles at the entrance. Little could be seen in this, as far as secondary nickel species.

The mine is hosted by the Forrestania Greenstone Belt, which is a south south-east trending continuation of the Southern Cross Greenstone Belt to the north.

I (Kim Macdonald) have found the geology of the area to be complex. Digger Rocks and Digger Rocks South are on the same lode. Both are located on a base, complex zoned ultramafic rock, 5 kilometres long and 425m thick.

For Digger Rocks the zones are from top down:
1. 100-150m thick preserved accumulate (meaning igneous crystalline rock from past volcanic activity) grading to bladed-granular fosterite-talc-anthophyllite-enstatite rock.
2. Forsterite-talc to fosterite-talc-anthophyllite to fosterite-talc-enstatite
3. Structually controlled main zone of nickel sulphide mineralisation, 240m long by 125m thick, of massive and disseminated sulphides, ranging to 7% Ni grades. It dips 50-65 degrees west, and pitches at 50 degrees north.
4. 10-75m thick ultrabasic footwall of alternating fosterite-tremolite-anthophyllite-enstatite. The footwall in the northern portion of the mine is banded iron formations, while the rest of the mine is a footwall ultrabasic unit. There is also a sliver 8-10m of quartz-biotite-garnet schist at the southern end.

For Digger Rocks South, the mine shows disseminated pyrrhotite-pentlandite-pyrite-chalcopyrite, as a homogeneous mass, 9-25m thick, dipping steeply west. There is supergene alteration to pyrite-violarite. Stringers of pyrrhotite-pentlandite-pyrite extend up to 20m into the banded iron formation footwall. In addition, there is a 200m long by 20m thick Ni sulphide zone found in the hanging wall of disseminated pentlandite-millerite and olivine grains.

Planned mining here is looking at mineralisation below the floor of the abandoned pit, with an eight year life span.

Mineral List

Anthophyllite Grunerite 'Hornblende'

Magnetite 'Olivine' Pentlandite

Pyrrhotite Talc Tremolite

Violarite

10 entries listed. 8 valid minerals.

References

External Links