On Mineral : Veins. 24:7 
the advance of the decomposition. Whenever quartz exists 
in lodes, the adjoining rock is more or less converted into 
kaolin, so that we find in the one place what is deficient in 
the other ; and when it is found that the abundance of ore 
in a lode is proportionate to the extent of the decomposition 
of the adjoining rock, this circumstance can only be regarded 
as a consequence of that decomposition.” 
This peculiarity may be noted even in the lower silurians 
of the western gold-fields of this colony, greatly changed as 
these all are ; but it is most marked where these rocks are 
hard and crystalline, as in some of our mountain ranges, or 
in the upper silurians ; for in the latter the cleavage (which 
is one indication of this decomposition) is imperfect, and 
only extends over limited areas, and-in consequence the 
veins formed in them have a corresponding character. 
When this decomposition has not penetrated far from the 
surface, the veins will soon die out, or become worthless ; 
but when the decomposition sets down to a great depth, the 
veins will do so likewise, and are as likely to bear ore below 
as at the surface. Auriferous veins are only an apparent 
exception to this rule, for although the rock may be rich in 
gold, yet the latter may be prevented from collecting in the 
veins, because a considerable portion of it has already been 
ageregated in the rock, and requires a second decomposition 
to liberate it. Cases may therefore occur where there has 
been a sufficient metamorphosis of the schists to allow of 
large quartz veins being formed at great depths from the 
surface, while the bulk of the gold may still be retained in 
the bounding beds. 
This apparent incongruity may be easily explained :—In 
| assisting the decomposition of the rocks and the ageregation 
(of its constituents in the veins, water no doubt acts an 
| important part, and with the exception of gold, the veins 
| are found to be as productive in metals at some distance 
below the water line as they are above that point. But this 
i is not always the case with auriferous quartz veins. Gold 
| is generally found intimately associated with the sulphides 
of iron, being aggregated along with them, and in auriferous 
| strata the iron ore, whether collected in the quartz veins or 
scattered in detached crystals through the rock, is seldom 
found without gold. This intimate association also exists in 
the case of the recent pyrites formed in the auriferous drifts, 
which invariably contain metallic gold incorporated with the 
| sulphide of iron. The same affinity may be illustrated by 
