ORES AND MINERALS ASSOCIATED WITH THE GOLD. 361 
The distribution of the gold in the gravel calls for a few remarks. Although 
the phenomena of this distribution are generally of a simple nature, and such 
as would naturally be expected to result from the disintegration and removal 
by water of a large mass of auriferous rock, yet there are some puzzling 
peculiarities, for which it is not easy to find an explanation. That a con- 
siderable part of the gold should be either lodged directly upon the bed-rock, 
or disseminated through the lowest layers of the gravel, nearly in contact 
with it, is easily understood. The tendency of the very heavy metal to sink, 
as the mass of detritus was being moved by the aqueous current, would be con- 
tinually exerted; and it is only the extreme fineness of the particles which 
has kept even a small portion of it from finding its way as far down as to the 
solid rock. 
In certain cases there is no gold at all upon the bed-rock ; but such 
instances are rare. There is nothing in these exceptional instances which 
need excite surprise ; for that in certain localities there should have been a 
covering of detritus spread over the surface of the bed-rock, coming from the 
disintegration of a quantity of rock which contained no gold, is very natural. 
It is not the case now, nor has it ever been, so far as we can judge, that all 
parts of the bed-rock have been impregnated with gold. Portions must 
have been entirely barren, and if the débris of such masses happened to 
find a permanent lodgment on the surface of the rock, and then become 
more or less consolidated, the particles of gold borne from other and richer 
regions would rest upon the underlying barren layers of gravel. 
Section VIII. — Ores and Minerals associated with the Gold. 
Some statements have been made in the preceding pages* in regard to 
the metalliferous ores which are most likely to be found accompanying the 
gold in the quartz veins. Something now remains to be said about the 
minerals and ores which have been detected in the gold-washings. These 
substances can, of course, be only such as are not too brittle or too easily 
oxidized ; for otherwise they would have been ground to powder in the 
process of the formation of the gravel, and would then have rapidly disap- 
peared, having been oxidized and dissolved away. If the metal gold is found 
so widely disseminated through the gravel and in river sands all over the 
world, it is because it is so very indestructible. It may be torn into very 
* See ante, pp. 56, 57. 
