34 On the Geological Distribution of Gold. 



teriorly, so that in a certain position it appeared to be one 

 single lump. The outlines were all rounded, the mass having 

 a rounded oval shape. Where it had been well cleansed from 

 the clay, there were marks seen all over similar to the 

 impression made by the point of a finger on clay. No 

 quartz was intermixed with the mass, but small quartz pebbles 

 were seen among the clayey earth still adhering to certain 

 inequalities. As the mass had not been perfectly cleaned, its 

 true yellow hue was only partially perceptible. The length 

 was about 18 inches, the greatest width about 13 inches. 

 The weight, as stated, was 2195 ounces ; its quality (by assay 

 of William Birkmyre, Esq.) 99,20 gold, 00,80 silver : thus 

 constituting the largest mass of, and purest gold yet found 

 in the world. 



The lowest quality of gold from Australia, being among 

 exceptions, is 62,50 gold, 37,50 silver; but most of the gold- 

 fields give gold from the fluvial deposits of from 93,00 to 

 97,95 ; wherefore of the known auriferous districts in the 

 whole world, Australia produces on an average the highest 

 quality, and as far as I have had an opportunity of observing, 

 when gold from the rocks is compared with that from the 

 fluvials of the same locality, the latter shows a less proportion 

 of silver. 



In some districts, the early fluvials carrying gold pro- 

 duce also another valuable metal, viz., platinum. In South 

 America, particularly in Chocd, and Barbacoas, platinum is 

 always found associated with gold, in the proportion of from 

 25 to 75 per cent. The appearance of this metal and its 

 usual associates is in small, flat, partly oblong, rather thick 

 grains, having well-rounded outlines, and always a clean, 

 bright surface. In Brazil, platinum is also found mixed 

 with gold, in about similar proportions ; but there the par- 

 ticles of this metal are seen in a fungiform or porous state, 

 and in rather larger grains. The residuum, or the black 

 sand accompanying the gold and platinum, from the said 

 localities, has generally been found to be titaniferous iron 

 oocidule, this being the " volcanic sand " of Berzelius. 



Platinum has been found in Santo Domingo, among auri- 

 ferous fluvials, also in small particles. The Ural Mountains 

 have produced great quantities of platinum, accompanied also 

 with fluvial gold. Platinum, though found among the auri- 

 ferous drift, is not known as existing in the rock, — its 

 " matrix " is supposed by some to be " talc." Its origin 

 is therefore unknown, and cannot be accounted for, like that 



