191

The sulphide minerals in the veins are oxidized for various distances
below the surface. The limited development of the veins prevents the
presentation of any reliable conclusions regarding the greatest depth of
oxidation, but it extends at least to 30 or 35 feet. Most of this oxidation,
as shown in the subsequent section dealing with the origin of the gold, is an
uneroded remnant of the Tertiary belt of weathering, which escaped
removal during the Ice Age.

So far as known no free gold occurs in the veins below the limit of
oxidation. The free gold that characterizes the upper parts of the veins
represents material released in Tertiary time, largely by the oxidation of
the arsenopyrite transported downward along the vein and deposited from
solution in the vicinity of the water table. This process is discussed in the
section already referred to on the origin of the placer gold.

The following are typical of examples of B veins:

(1) The series of northeasterly-trending veins on the Proserpine surveyed claim, near
its southwestern line, on one of which the old Forrest shaft was sunk to a depth of 60 feet.
The veins vary in width up to 2 feet and are well mineralized with pyrite, arsenopyrite,
and galena (See sketch map of claims on Proserpine mountain.)

(2) The series of northeasterly-trending veins on the Warspite and Tipperary surveyed
claims on Proserpine mountain (See sketch map of claims on Proserpine mountain.)

(3) The Beedy or Perkins ledge on Burns mountain, about 2 miles east of Stanley

5

(Van Winkle). Here there are several parallel, northeasterly-trending veins, varying in
width up to 2 feet, containing pyrite and galena, with considerable free gold in the upper,
oxidized parts.

(4) The scheelite-bearing veins of Hardscrabble creek, ! 7 miles northwest of Barker-
ville. These are quartz-ankerite-siderite veins carrying pyrite, galena, and scheelite.

The B veins are believed to have been formed after the building of the
anticlinal structure in the Cariboo series and before the deposition of the
Slide Mountain series. This belief is based on the fact that the veins
crosscut the schistosity and the zones of shearing of the Cariboo series,
and are not mineralized with sulphides where the fractures extend upwards
into the Slide Mountain series. After the deposition and folding of the
Slide Mountain series, the tendency of the country to settle back reopened
the B fissures, and the movement of one wall over the other brecciated the
more resistant vein minerals, pyrite, arsenopyrite, quartz, and siderite,
and forced the less competent galena to yield by flowage.

The metallization of the veins, including the formation of the gold,
cannot be definitely attributed to the effect of any observed petrological
agent, but the mineralogy and structure of the deposits suggest that the
metallic minerals owe their origin to emanations from intrusive rocks,
whose location is inferred to be at comparatively short depths below the
lowest exposed member of the Richfield formation, and of whose presence
there the Proserpine quartz porphyry sills may be a manifestation.

Intersections of A and B Veins

Shoots of sulphide minerals are observed in the field to occur in veins
of the A type where the latter are intersected or met by a number of B
veins carrying metallic minerals. The reason for the localization of bodies

Reha T.L.: ‘‘Report on Tungsten Ores of Canada’’; Mines Branch, Dept. of Mines, Canada, Pub. No. 25
20285—13}