GOLD MINING

Hokitika Guardian, 8 October 1929, Page 2

GOLD MINING

TAKING OF GOLD FROM BLACK SAND. Machines having magnets to separate the iron or magnetic portion of the .sand from, the rest have been made, but they have found that only about 10 per cent, of the sand is magnetic. While running the sand through these machines some of the flakes of gold and the particles of grey sand that happen /;o get caught between the grains of magnetic sand and the magnets are taken out with the magnetic sand making the separation unsatisfactory. The black sand found in the bottom of the sluice boxes in hydraulic mines is almost all strongly magnetic, but the black sand found on the beaches along the coast does not resemble this sand much. The gold is so light that if it is not thoroughly wetted before it goes into the sluice-box the chances are that it will have a small a : r bubble attached to its side and rise to the top of the water and float off without sinking at all. Nearly all the beach sand carries platinum and iriclum in the form of grains like the rest of the sand. Rubios are occasionally met with in the black sand.

In general tho valuable black sand may be described as consisting of hard minerals ranging in specific gravity from. 3 to 7, mingled with small percentages of metals and metallic minerals reaching from 7 to 21 in' specific gravity. Most of the value will be found in the sand below A in diameter of its grain. The black sands as here described should be considered as the concentrates of the gravel deposits and may be compared with the concentrates obtained in milling the metalliferous ores to which they are related, and from which they are partly derived. Their treatment should in essentials, follow the rules that experience has dictated in manipulation of gold or°s; It is true that anyone contemplating the solution of the problem must he prepared for many failures at first. The ultimate success of all metallurgical innovations in the past has only been attained at the cost of many failures. From each failure we have learned some lesson and drawn some experience until at last the amount of inexperience was sufficiently small to he overcome at one time and these features must he kept in mind by all who would make the attempt.