An experimental study on gold solubility in amino acid solution and its geological significance

The experiments on gold solubility in amino acid solution indicate that gold is very intensively soluble in amino acid (or other organic acids), which is extensively present in geological bodies, and is most soluble in histidine. The temperature and concentration, acidity and type of amino acid in the solution are important factors affecting gold-amino acid complexing. The solubility of gold in amino acid is different under different conditions of temperature, amino acid concentration and pH value of the solution. At 80°C and pH=6–8, gold is most soluble in amino acid. Gold dispersed in water and rocks could be concentrated and transported by amino acid and then precipitated in favorable loci. Amino acids might have played an important role in metallogenesis as well as in the formation of source beds of gold. Nitrogen, oxygen and sulfur in amino acid might have reacted with gold to form soluble complex ions.