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dc.contributor.authorHough, R.
dc.contributor.authorButt, C.
dc.contributor.authorReddy, Steven
dc.contributor.authorVerrall, M.
dc.date.accessioned2017-01-30T13:36:08Z
dc.date.available2017-01-30T13:36:08Z
dc.date.created2008-11-12T23:32:43Z
dc.date.issued2007
dc.identifier.citationHough, R.M. and Butt, C.R.M. and Reddy, S.M. and Verrall, M. 2007. Gold nuggets: supergene or hypogene? Australian Journal of Earth Sciences 54 (7): 959-964.
dc.identifier.urihttp://hdl.handle.net/20.500.11937/33276
dc.identifier.doi10.1080/08120090701488289
dc.description.abstract

Native gold in placers and intensely weathered rocks commonly occurs as grains (less than 500 μm) and, more rarely, as large (greater than 4 mm or 1 g) nuggets. There has long been speculation about whether gold nuggets, especially those found in deeply weathered regolith environments, are supergene or hypogene in origin. An examination of the external and internal characteristics of more than 30 nuggets from different locations in Western Australia, Queensland and Victoria, ranging from 1 g to greater than 8 kg, was carried out. All of these nuggets are composed of gold - silver alloys, typical of hypogene gold. Furthermore, each has a polycrystalline internal structure that is characteristic of high temperature (greater than 250C) thermal annealing. All of the nuggets also exhibit corrosion features, including pits, voids and silver depletion that are due to weathering. The silver depletion is strongly controlled by the crystal structure and proceeds along crystallographic grain boundaries by a selective solution process equivalent to depletion gilding. Polycrystalline Au - Ag nuggets with the characteristics presented here are hypogene in origin, concentrated at the surface as the residue of prolonged exposure, weathering and erosion of gold deposits, not by supergene growth.

dc.subjectgold nuggets
dc.subjecthypogene
dc.subjectsupergene
dc.subjectsilver depletion
dc.subjectcrystallography
dc.subjectannealing
dc.titleGold nuggets: supergene or hypogene?
dc.typeJournal Article
dcterms.source.volume54
dcterms.source.number7
dcterms.source.monthoct
dcterms.source.startPage959
dcterms.source.endPage964
dcterms.source.titleAustralian Journal of Earth Sciences
curtin.note

This is an electronic version of an article published in: Hough, R.M. and Butt, C.R.M. and Reddy, S.M. and Verrall, M. (2007) Gold nuggets: supergene or hypogene? Australian Journal of Earth Sciences 54(7):959-964.

curtin.note

Australian Journal of Earth Sciences is available online at:http://dx.doi.org/10.1080/08120090701488289

curtin.identifierEPR-2372
curtin.accessStatusOpen access
curtin.facultyDepartment of Applied Geology
curtin.facultyDivision of Resources and Environment


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