ORIGIN OF GOLD NUGGETS. oe 
Prof. Egleston, in his work upon Metallurgy of Silver, Gold, 
and Mercury in the United States (New York, 1887, Vol. 11., p. 57) 
takes up the question of the origin of nuggets, and quotes a letter 
from Mr. Selwyn, 28th March, 1882, in which Mr. Selwyn stands 
by his original hypothesis as follows :—‘“ The cause (7.e. of nuggets) 
was the percolation through the gold bearing strata of very large 
quantities of saline and acid thermal waters, during the period of 
great volcanic activity, which produced the basalts. This action 
accompanied, but to a great extent succeeded, the phenomena 
which produced the present placer deposits. This gold from 
meteoric waters deposited on that already in the sands, produced 
the nuggets. He further states that his opinion is confirmed by 
the fact that large nuggets only are found in the western gold 
fields, as at Ballaarat, Daisy Hill, &c., where immense basaltic 
eruptions had taken place all over the district. In the eastern 
and northern districts, as Gippsland, Ovens, &c., where streams 
of basalt occur only to a very limited extent, or are altogether 
absent, the gold is generally very fine, and nuggets over one ounce 
in weight are of the greatest rarity.” Brough Smyth, however, 
states otherwise (see p. 311). 
Prof. Egleston urges that in cases where the ‘gold does come 
from the destruction of veins, the surfaces are rounded and worn 
smooth.” .. . “This is in entire contradiction to the mammillary 
structure of the nuggets.” . . . They would have been water worn 
on the outside, and the cavities “‘ would have been in the condition 
in which they left the vein, and the edges of any crystals found 
there would have been sharp; while in the nuggets the mammillary 
form exists even where crystals or the commencement of crystallisa- 
tion is observed, the edges of the crystals are very often blunted 
or rounded, showing both deposition and solution on these edges.” 
Egleston also urges, as others have done, that if the gold had 
come from the eroded rocks it should have the same composition 
as that of the veins of the district in which it is found ; whereas 
he says it is well known that vein gold is usually poorer than the 
alluvial gold of the same district, e.g , 
