'MAGNETIC' NATIVE GOLD

Abstract

A puzzling feature in the mineralogy of gold was the presence of native gold with uniformly strong magnetic susceptibility, considered to be a solid solution of iron in gold. The authors investigated what was described as 'magnetic' native gold from Yakutian placers. Judging by published reports, specimens of such gold with 3 to 4 percent Fe are known in ore deposits of the Urals and Kolyma River region. The iron content of normal native gold, as determined by electron-microprobe analysis, ranges from traces to 0.2 weight percent. Both large and small specimens are uniformly magnetic. Thus, they established by various methods that 'magnetic' native gold is not a solid solution of iron in gold, as earlier supposed, but is a matrix of silver-rich gold with inclusions of minute magnetite crystals. It also contains about 0.1 percent copper.