9

Melting some refined gold.

Reprocessing gold from scrap is always a good source of this shiny precious metal, in this case a 15 g button. Gold is a relatively low melting point (1337.33 K ​(1064.18 °C, ​1947.52 °F)) what means it could be melt with a methane/oxygen torch. The other good point when melting gold, compared to melting silver is that it needs no borax flux what should be used when melting silver to prevent the oxidation of the molten metal.

Interesting fact: 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.

Fritz Haber (the German inventor of the Haber process) did research on the extraction of gold from sea water in an effort to help pay Germany’s reparations following World War I. Based on the published values of 2 to 64 ppb of gold in seawater a commercially successful extraction seemed possible. After analysis of 4,000 water samples yielding an average of 0.004 ppb it became clear that the extraction would not be possible and he stopped the project. No commercially viable mechanism for performing gold extraction from sea water has yet been identified.

More info: https://en.wikipedia.org/wiki/Gold