Saturday, September 24, 2011

Australian Journal of Mineralogy Volume 4 Number 1

Cover Photograph: Wulfenite, Whim Creek, Western Australia, 5mm long crystal, Photo: Ted Madden

The Mineralogy of the Oxidised Zones of the E22 & E27 Orebodies at Northparkes, New South Wales
M Crane, J Sharpe and P Williams

The E22 and E27 deposits at Northparkes have well-developed oxidised zones overlying thin secondary enriched zones. The main secondary minerals present are malachite, azurite, chrysocolla, libethenite and pseudomalachite. The distribution of these minerals is zoned, with copper phosphates occurring in the upper sections and copper carbonates dominating at depth. Chrysocolla commonly forms overgrowths on libethenite and azurite, which may later dissolve to leave chrysocolla endomorphs. The presence of visible gold in the lower oxide and supergene enriched zones suggests gold has been remobilised by the weathering of sulphides and enriched down profile. Native copper, cuprite, tenorite, chalcocite and digenite have been identified in the enriched zone.

End-Member Beyerite from the Alone Hand Mine, Cloncurry, Queensland
L Lawrence, A Ramsden, J Sharpe and P Williams

End-member beyerite, (Ca,Pb)Bi2(CO3)2O2 has been found at the Alone Hand mine, south of Cloncurry, Queensland. It occurs as an alteration product of bismuthinite in the oxidised zone of a gold-bearing orebody whose primary and secondary mineralogy is described. New data is given for beyerite from the Alone Hand, this being the first recorded Australian occurrence of the mineral and the first in which Ca is not partially replaced by Pb.

The Minerals of the Whim Creek Copper Mine, Western Australia
P Downes, J Bevan and A Bevan

For more than a century, the Whim Creek Mine has been the source of fine copper and lead minerals. In all, more than sixty minerals species have been recognised from the mine and includes the first recorded occurrence of murdochite in Australia.

Platinum Group Minerals from the Broken Hill District, New South Wales
S Elvy, N Gray, J McAndrew, P Williams and D French

Small deposits containing high platinum and palladium grades occur to the east of Broken Hill, New South Wales. Gossan samples have been examined from Mulga Springs, Little Darling Creek and Round Hill (Moorkaie Hill) to identify any platinum group minerals present. Platinum mineralogy is simple, being confined to braggite, sperrylite and native platinum, the latter being derived from oxidation of sperrylite. Palladium mineralogy is much more complex. Species found include Pd-Cu alloys, froodite, mertieite II, paolovite and several unnamed phases corresponding to (Cu,Pd)3Bi, Pd20(Te,Bi)3 and Pd3(Te,Hg)3. Copper-palladium oxides also occur, associated with goethite, malachite and chrysocolla. Secondary base metal mineralogy is also described. This is the first detailed report of the platinum group mineralogy of these deposits.