Description: �Production of platinum, gold, and silver in North America in 1913� Each dot represents 1 per cent of world�s production. A cross represents less than 1/2 per cent of world�s production. In Mexico all producing districts are indicated by crosses and only the total production is shown by dots. — Department of the Interior, 1921
Source: Department of the Interior , World Atlas of Commercial Geology (Washington, DC: Department of the Interior , 1921) Plate 42
Map Credit: Courtesy the private collection of Roy Winkelman |
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