Cocanarup pegmatite field, Ravensthorpe Shire, Western Australia, Australiai

Regional Level Types
Cocanarup pegmatite field	Pegmatite Field
Ravensthorpe Shire	Shire
Western Australia	State
Australia	Country

Located 19 kilometres south-west of Ravensthorpe.

This was once a fossicking site, however presently (2012) the lease is owned by Galaxy Resources, who operate the nearby Mt Cattlin Lithium Mine. The Mine Manager has advised me they are not allowing the public to fossick at the Cocanarup site. The entry has been included for anyone with historic specimens from the location before fossicking was banned.

The pegmatites were discovered in 1900, at the same time as the Mt Cattlin pegmatite, however the Cocanarup field is significantly less mineralized. The field consists of pegmatites named Quarry, Horseshoe, Eastern and Crescent. Quarry is northern most, with Eastern approximately 500 metres east, Horseshoe 1 kilometre south of the Quarry pegmatite, and Crescent further south again of Horseshoe.

No active mining took place on the field until 1960-63 when 13.3 tonnes of beryl was mined from the Quarry pegmatite. During 1980-1994, Amax Australia, Chevron, and Noranda Australia all explored the area, but found the deposit to be uneconomic. Amax Australia did however map the pegmatite field for the first time. They noted lepidolite at Horseshoe, zinnwaldite at Eastern, lepidolite and columbite at Quarry, and no lithium minerals at Crescent. Further exploratory work was done by UCABS PL from 1996-1999 and determined the deposit contained high grade potash feldspar used in glass making and ceramics, but could not find a market. In 2001 Galaxy Resources took over the leases.

As the name suggests, the only pegmatite to see active mining, exposing the minerals below the surface is Quarry pegmatite. The pegmatite is approximately 1200 metres long and 15 to 40 metres in width. It dips 20 degrees to the west. The quarry itself at Quarry pegmatite shows albite variety cleavelandite, containing zinnwaldite, fine grained lilac coloured muscovite, a wall zone of quartz-plagioclase-muscovite with abundant schorl on its outer edges. Small quartz core segments are exposed at the northern side of the quarry.

The Eastern pegmatite runs for 2000 metres north-south, and is 10 to 70 metres wide. The Horseshoe pegmatite is 700 metres 'tall' and 500 metres wide and as the name suggests is U shaped. It ranges in thickness 40 to 100 metres. Amax mapping indicates it contains abundant lepidolite and tourmaline. Crescent pegmatite is 700 metres wide and 1 kilometre long, quartz-microcline-muscovite with minor schorl.

Deep blue, pink and green elbaite have been reported from the pegmatites, but remains largely unexplored from a specimen collecting viewpoint.

References

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