and dip and cannot be grouped into any fracture system on the basis of their attitude.
Widths of quartz in these ‘‘B” veins may reach as much as 6 feet, and in general they
are wider than the north-north-easterly striking veins. For the most part, the quartz
‘is devoid of sulphides or only sparsely mineralized with pyrite, galena, and more rarely
sphalerite. Sampling of these veins, wherever seen, reveals that they contain little
gold, if any (see Table IX, p. 57).

MINERALOGY.

The mineralogy of the veins is simple. The quartz is milky in appearance, usually
only slightly fractured, if at all, and may in places contain a few small crystal-lined
cavities. Ankerite or siderite* is a common, but not universal, constituent of the veins.
It may occur as small masses or disseminated grains, and frequently forms narrow
selvages along the vein-walls. An analysis of ankerite+ from quartz-pyrite veins in the
long crosscut driven by Burns Mountain Gold Quartz Mines, Limited, on the south side
of Burns Mountain is: FeCOs, 65.6 per cent.; CaCOs, 1.4 per cent.; MgCOs, 29.9 per
cent.; and MnCOs, 3.2 per cent.

Pyrite is the commonest of the sulphides and is present, in exceptional instances,
in amounts ranging up to half the vein, but the average pyrite content is less than 5
per cent. The pyrite may be present as irregular masses ranging up to several inches
across, but more frequently occurs in small individual crystal grains or clusters of
crystals. The cubical pyrite crystals generally measure less than one-quarter of an
inch along their edge, but may reach half an inch or larger. Pyritization of the wall-
rock frequently accompanies pyrite-bearing quartz veins, and fairly abundant coarse
cubical crystals are developed in the wall-rock for several inches or considerably greater
distances away from the veins. The intensity of the pyritization of the rock appears
to depend on the number of and degree of mineralization of the adjacent quartz veins.

Galena in small amounts accompanies pyrite in several of the Perkins veins on
Burns Mountain, in the Foster Ledges and several other small veins in Oregon Gulch,
in veins on the Acme group, and elsewhere.

Sphalerite, subordinate in amount to the accompanying pyrite and galena, is
present in the Foster Ledges at the forks of Oregon Gulch, and in the vein-segment in
the fault-zone exposed in a hydraulic pit near the west end of the Slough Creek bench
close to Nelson Creek.

Free gold has been seen in quartz from the dumps of the Perkins veins on Burns
Mountain, in the veins on the Acme group north of Stanley, and has been reported from
the Foster Ledges at the forks of Oregon Gulch. The Perkins veins produced several
spectacular specimens of free gold in quartz variously reported to be valued between
$30 and $120 (Johnston and Uglow, 1926, p. 209).

The gold in specimens from the Perkins veins and the veins on the Acme group is
most frequently seen either in cubical cavities from which pyrite has been completely
leached or in cubical masses of limonite resulting from the oxidation of pyrite, and
more rarely in quartz that is otherwise unmineralized. Most of the gold seen in vein
specimens or recovered by panning oxidized vein material is very small, considerably
smaller than the bulk of the fine gold recovered in placer operations.

MINERALOG:C ASSOCIATION OF GOLD.

The variable mineralogic association of gold is shown by the following tabulated
assay results (see Table I) :—

* The composition of the vein carbonate has not been investigated. It is, in this report, called ankerite.
+ This material, a magnesian siderite, is more properly called pistomesite.

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