Gold mineralogy
Natural resources of elemental gold are mainly contained in the mineral gold (plus 85%Au) and in seawater. The oceans contain a major resource of gold in solution but individual estimates are variable, depending upon the location of samples, which appear to range in gold content from as low as 0.1 to as high as 2.0 ppb by weight. Emery and Schlee (1963) note gold grades in the top 10m of sediments in the Atlantis 2 Deep between 5 and 10 ppm. However, attempts to recover gold from seawater on a commercial scale have so far failed, mainly because of the large quantities of water involved; ion exchange appears to offer the present best avenue for research. Salt, bromine and magnesia are recovered from seawater on a large scale hence the oceans must be regarded as a potential gold source of major proportions.
Element associations are broadly classified on the basis of their affinities for metals, sulphides, silicates or gas phases, and are referred to in Table 1.1 as sidero-phile, chalcophile, lithophile and atmophile respectively (from Goldschmidt,1922). Basically a siderophile element, gold has some characteristics that relate it to chalcophile group elements. The general ubiquity of gold is
Demonstrated in Table 1.2, which shows common element associations in a range of ore deposit types.
