The spherical form of gold; man-made or secondary?
| Autor: | R. N. W. DiLabio, J. W. Newsome, D. F. McIvor, P. L. Lowenstein |
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| Rok vydání: | 1988 |
| Předmět: | |
| Zdroj: | Economic Geology. 83:153-162 |
| ISSN: | 1554-0774 0361-0128 |
| DOI: | 10.2113/gsecongeo.83.1.153 |
| Popis: | An unusual spherical form of gold is described from a number of widely distributed sites: the Abitibi clay belt of Canada, the Lakekamu gold field of Papua New Guinea, the Naraguta placer tin mine in Nigeria, French Creek in British Columbia, Chateau-Gontier in France, the Dorlin area of French Guiana, a gossan in Cyprus, and three placers in South America. The spheres range in size from 20 to 300 mu m and are characterized by a microcrystallite structure, variable gold contents from site to site, and significant amounts of silver and copper. Some of the spheres are interpreted as secondary or supergene chemical precipitates produced by the reduction of gold in ground water and soil water by iron and manganese oxides: most are interpreted as man-made melt droplets accidentally introduced into otherwise normal placer samples, and some may be interpreted either way. Whenever they are found during a gold exploration program, the geologist should suspect that the samples concerned have been contaminated with man-made melt droplets. |
| Databáze: | OpenAIRE |
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