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dykes and sills may be as much as 200 fect wide and continuous

for miles. There are also laccoliths where sills widen out and
assume mushroom shape, and small stocks. Some of the grano-
diorite of the extensive arcas to the south is belioved to be of
the same character, but large areas in the east are of the younger
andesine granodiorite and there are bodies of hornblendite, cdiorite,
and syenite that are not believed to be related to the albito-rich
intrusives,.

Mineral deposits, which are fairly abundant, have been
found near, or less commonly in, practically all stocks of the
albite-rich intrusives and in, or less commonly near, laccoliths
and dykes. Sills show a little, but in the main unimportant,
mineralization. The deposits are mainly small veins of quartz
with some carbonate and carry pyrite, black sphalerite, galena,
free gold, minor BOs of chalcopyrite, and less commonly,
pyrrhotite. Many assayed samples carries more than one ounce in
gold, but only relatively low values in silver. Other deposits,
either woll mineralized or sparsely mincralized, carry low valucs

in gold. as

Most of the important deposits that occur outside but
near intrusive bodies lie along bedding planes below massive beds
of conglomerate or tuff and near or over anticlinal axes. The
deposits formed in such positions are almost invariably thickest
on the crest of the fold and thinner down the dip. The Black Bear,
Black Wolf, Fiddler, and many less important veins arc believed

to be of this type. A zone of possible merit on the Scenic and

Log Cabin groups may be of this type or it may not be related to
the bedding. Im the sediments in many places, especially near
these veins, innumerable, small veins fill fractures chat have

resulted from the folding or other causes.