ORIGIN OF GOLD NUGGETS. S17 
Composition of Vein and Alluvial Gold, 
In the preceding references there are several statements as to 
the greater purity of alluvial gold over vein gold, and this is by 
many assumed to be a proof that the nuggets and other forms of 
alluvial gold have had a different origin to the vein gold and that 
- the alluvial gold has been deposited in the way suggested by 
Selwyn and other writers.. 
If we examine some of the assays of vein and alluvial gold, we 
shall see that there are differences but that they are not very 
material, and further the vein gold is sometimes richer than the 
drift gold. 
Selwyn and Ulrich (P.G. G. and Min. of Vict., 1866) p. 42, 
refer to the greater richness of alluvial gold. 
D.C. Davis, F.4.s.—Metalliferous Minerals and Mining ( London, 
1880, p. 50) in speaking of “the gold bearing drift of the Sierra 
Nevada says, the particles of gold are found of larger size and 
contain more silver at the bottom than at the top of the ancient 
drift, and are worth less by two shillings and sixpence per ounce. 
It is supposed that their difference in quality is caused by the 
larger size of the fragments below resisting more effectually the 
action of sulphuric acid which, set free by the decomposition of 
pyrites, has eaten the silver out of the smaller grains at the top 
of the deposit. 
He also says, p. 36, “Gold is most plentiful in it (drift in the 
Urals) where the drift is most largely charged with iron ;” and 
Brough Smyth, in a Report on the Gold Mines of the S.E. portion 
of the Wynaad, &c. (London, 1880) states that “ the gold obtained 
in the Wynaad is unequal in fineness, that from the soils being of 
the best quality. It has been observed in other countries that 
the finer the particles of the gold procured from alluvial deposits 
the higher is the quality.” 
»P. Nisser—On the Geol. Distribution of Gold, with special 
reference to some Auriferous Rocks in South America (Trans. Phil. 
Institute, Vict., 1v., 1860, read 30th March, 1859) points out 
