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a uniformity in the number and size of veins even though the veins at
the three levels are all different. It would seem that uniformity is well
enough established that its persistence to deeper and higher intermediate
levels can be taken for granted and that any favourable block of ground in
a vein zone can be counted on to supply an average amount of ore without
previous blocking out of the veins. The more extensive the mining
development the more accurate will be the estimate. As the veins are
narrow obviously the profit from individual veins cannot be great and would
be reduced considerably if development were so done as to block out each
vein.

In the northwestern part of the belt the Rainbow member, because it
lies between the B.C. and the Baker members and will consequently be much
fractured, offers decidedly the best opportunities for the discovery of trans-
verse and diagonal veins. In this part of the belt veins of this type are
expected to be numerous. Better veins than those already discovered cannot
be expected, but development should disclose approximately the same condi-
tions as obtain in the workings of the Island Mountain and Cariboo Gold
Quartz mines.

In the southeastern part of the belt the Rainbow member is not clearly

‘the most valuable part of the belt. In this part of the belt the Rainbow and
Lowhee members adjoin, are much alike in rock type, and presumably also
in numbers and size of veins. The body of the rock in which the stresses
would be relieved is much wider as it there includes two members, and, there-
fore, veins may not be so numerous per unit of area as they are where the
favourable fracture belt is narrow.

Replacements of limestone appear to be very closely tied up with the
transverse and diagonal veins. So far ore of this type has been found only
in the Rainbow member and at the base of the Baker member. At the
Cariboo Gold Quartz mine ore of this type occurs mainly where veins are
numerous. This relation may not hold at the Island Mountain mine, but
the source of the ore there is believed to be veins. In the northwestern part
of the belt search for ore of this type should be confined as far as practicable
to the two members in which ore-bodies of this type are known to occur.
Whereas exploration for veins must be carried out mainly by tunnelling,
search for replacements can be carried out by either of two methods. One
method would be to diamond drill across the strata in order to locate beds
of limestone, for the replacements occur only in limestone. The replace-
ments may also be amenable to location by some methods of geophysical
prospecting. It is an easy matter to locate limestone beds on the surface
or by means of diamond drilling and the field of geophysical search can be
confined to the immediate vicinity of the beds discovered.

The value of the veins parallel or roughly parallel to the strata has
not been demonstrated. Most veins of this type in the belt are much
wider than those crossing the strata and if they are ore bearing they may
provide larger tonnages. None has been shown to he commercially
valuable. In view of the apparent concentration of gold into the Rain-
bow member the veins of this type occurring in this member would pre-
sumably have the best chance of being ore bearing.