http://en.wikipedia.org/wiki/Gold
The world's oceans contain gold. Measured concentrations of gold in the Atlantic and Northeast Pacific are 50–150 fmol/L or 10–30 parts per 1,000,000,000,000,000 quadrillion (about 10–30 g/km3). In general, gold concentrations for south Atlantic and central Pacific samples are the same (~50 fmol/L) but less certain. Mediterranean deep waters contain slightly higher concentrations of gold (100–150 fmol/L) attributed to wind-blown dust and/or rivers. At 10 parts per quadrillion
the Earth's oceans would hold 15,000 tonnes of gold.[83] These figures are three orders of magnitude less than reported in the literature prior to 1988, indicating contamination problems with the earlier data.