203

and mineralized with granular pyrite. Some of these veins have been
found to be quite rich in gold; most of them, however, are narrow and
lensy.

A different type of mineralization is represented on the Jupiter prop-
erty in fissures that are older than the pyrite-bearing fracture zones. These
fissures have been healed by quartz-calcite veins mineralized with sphal-
erite, galena, tetrahedrite, chalcopyrite, and minor pyrite, and contain, in
places, more than 200 ounces of silver a ton. The known veins are for the
most part less than a foot wide.

Lens-like replacement bodies of pyrrhotite and pyrite, with some
chalcopyrite, occur in the argillite on Polaris Creek near small stocks and
dykes of granite and andesite porphyry. These bodies, which are com-
posed almost entirely of sulphides, attain a width of 25 feet and a length of
several hundred feet, but none has been found to contain appreciable
amounts of the precious metals.

Deposits YouNcER THAN THE Post-PALEOCENE FAULTS

The carbonatized fault zones cutting the Takla group and late Palso-
zoie rocks contain a little cinnabar near Tutizika River, on the Vega
mineral claims, and near Thane Creek, These fault zones appear to be
part of, or related to, major, northwest-trending faults that have displaced
all of the rock-units in the map-area. The only cinnabar deposits that
have been explored are those on the Vega group of claims.