Editing Gold nugget (section)

==Composition==
Nuggets are usually 20K to 22K purity (83% to 92% by [[mass]]). Gold nuggets in [[Australia]] often are 23K or slightly higher, while Alaskan nuggets are usually at the lower end of the spectrum. Purity can be roughly assessed by the nugget color, the richer and deeper the orange-yellow the higher the gold content. Nuggets are also referred to by their [[fineness]], for example "865 fine" means the nugget is 865 parts per thousand in gold by mass. The common impurities are [[silver]] and [[copper]]. Nuggets high in silver content constitute the alloy [[electrum]].<ref>{{cite book|last=McLaren|first=J. Malcolm|title=Gold: Its Geological Occurrence and Geographical Distribution}}</ref> The chemical composition of supergene gold nuggets can reveal the characteristics of the primary ore.<ref>Horbe, A. M. C., Martins-Ferreira, M. A. C., & Lima, R. S. (2019). Supergene gold characterization by geochemistry, grain morphology and Au-Ag-Cu-Te classification. Journal of South American Earth Sciences, 95, 102315.</ref>