Distribution of gold deposited under reducing adsorption from HAuCl4 solution on magnetite, sphalerite, and galena crystals

A statistical analysis was carried out for the concentrations of gold depos ited under reducing adsorption from hydrochloric acid solutions of Au (III) at the surfaces of hydrothermally grown crystals of sphalerite, galenite, and magnetite. Gold is confirmed to adsorb as a metal. It is shown that sor ption and reduction of gold are more effective for galenite: The average Au content is nearly an order of magnitude higher than those for sphalerite a nd magnetite. The variation coefficient of gold concentrations is 55% for m agnetite, 144% for sphalerite, and 146% for galena, i.e., is considerably h igher than 20% - a limiting value for determining the proportion of structu rally bound gold by Tauson's method (1998). It is shown that reducing adsor ption of gold is less effective on crystals of sizes 1.4-1.8 mm (efficient diameters) as compared with smaller ones, which may be related to a lower d ensity of surface defects in them.