Eardleyite as a product of the supergene alteration of nickel sulfides in Western Australia

E. H. Nickel; C. E. S. Davis; M. Bussell; P. J. Bridge; J. G. Dunn; R. D. MacDonald

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Other| June 01, 1977

Eardleyite as a product of the supergene alteration of nickel sulfides in Western Australia

E. H. Nickel;

E. H. Nickel

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C. E. S. Davis;

C. E. S. Davis

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M. Bussell;

M. Bussell

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P. J. Bridge;

P. J. Bridge

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J. G. Dunn;

J. G. Dunn

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R. D. MacDonald

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Author and Article Information

E. H. Nickel

C. E. S. Davis

M. Bussell

P. J. Bridge

J. G. Dunn

R. D. MacDonald

Publisher: Mineralogical Society of America

First Online: 03 Mar 2017

Online ISSN: 1945-3027

Print ISSN: 0003-004X

American Mineralogist (1977) 62 (5-6): 449–457.

Abstract

Eardleyite, a Ni-Al member of the pyroaurite group, has been found in the weathered crust overlying nickel sulfide deposits in four localities in Western Australia. Chemical analysis of material from the Perseverance deposit near Agnew indicates a composition corresponding to Ni_4.94Mg_0.10Ca_0.02Fe_0.13Al_2.81(CO₃)_2.27(OH)_14.42·5.42 H₂O. Samples from other localities show a Ni-Al atomic ratio varying between 1.19 and 2.03, which is substantially below the 3:l ratio expected in a pyroaurite-type mineral. The relatively high Al content is accompanied by a high carbonate content, which suggests a charge-balancing mechanism, as expressed by the general formula: Ni_6−xAl_2+x,(OH)_18−x−y(CO₃)_x+1/2y·nH₂O. Thermal and mass spectrographic analyses indicate evolution of water at 260°C and of water and CO₂ at 370°C.