The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-06-19

spicuous crystals of garnet or cyan
lite. The argilIaceous beds are repre-
scented by coarse mica schists, garnet
ferrous for the most part. some of the
garnets in which are nearly as large
as a tennis ball. Pegmatitic material
permeates these rocks very intimately
in the form Of minute veins or lenses
parallel to the bedding and even in
isolated feldspar crystals. The rocks
where this material Is abundant are
properly characterized as injection
gneisses. The foliation Of the grant
old gneisses and sheared anorthositt
shows most clearly how large a part
pressure as well as heat has played in
the metamorphism. OF all the igne-
Gus rocks. the diabases have suffered
the most radical change of texture
and mineral constitution. Where
Imetamorphism is thorough the dia
base Is altered to black schistose
amphibolite studded with red garnets
liberalization.
naturalization Of the country rock
by the introduction of specks or grains
Of such minerals as pyrite, chalcopy-
rite and siderite Is found in certain
formations or under certain condi-
tions. The most noteworthy example
Of this is the occurrence of grains of
siderite (spathic from generally dis
seminated in the sandstones of the
strata representing the lower part of
the Newland (Wallace) formation. ST.
derite Is somewhat more sparingly
present In the sandy shales also. This
phenomenon Is most characteristic Of
the areas Of complex structure. This
mineral replaces other constituents of
the rock in a way similar to the mode
of its occurrence in the Occur d'Alene
district. where, however. 1t is found
in the Burke and Revett quantities. in
stead of In the Newland (Wallace)
formation, The BLUSH greenish
shales and slate which represent the
upper part of the Newland formation
| show little or no general mineraliza-
ton except sparing distribution of
pyrite in some areas. The strata rep
resenting the Burke and Revett form
atIons and the lower quartzites and
schists contain specks and crystals of
pyrite more or less generally dissem-
mated and in small area little chal-
copyrite.
Local Features.
Lodes of the more or less pockety
or replacement type are numerous in
certain areas. mainly those occupied
by the strata representing the lower
part Of the Newland formation. All
Of the lodes contain chalcopyrite and
pyrite as the chief or among the chief
ore minerals. Galena and sphalerite
are found in small area. Siderite
Is the chief gangue mineral in most of
the lodes; quartz and calcite in 9TH
ers.
Crushed zones and fault breccias
found in the sandstones of the New
land formation are usually cemented
to a greater or less extent by siderte
and some calcite.
! Sheared zones in the diabase are
generally mineralized by the introduce
tion of calcite. quartz and siderite that
form knife blade" seams or veinlets
and irregular punches and by the in
PRODUCTION also of varying amounts of
pyrite and chalcopyrite.
Assay Values.
Some reported assay values are
given in the descriptions Of the pros
poets. from which it appears that the
lodes containing pyrite and chalcopy-
rite carry up to $40 or more to the
ton in gold and a little silver. In
addition assays of samples collected
in the field indicate that in general
the outcrops Of the large sideritic
lodes contain traces of gold and lit
tie silver usually less than l ounce to
the ton and that outcrops of the
sheared zones in diabase showing
knife blade seams of quartz or calcite
contain from traces up to $3.50 to the
ton In gold, from traces up to four
ounces Of silver to the ton and traces
0ess than OIL per cent? of copper. AS
says of the lodes showing galena,
"halcopyrite or pyrite other than the
reported ones referred to are not at
his time available.
Conclusions.
In the st. Joe and Black Prince
creek areas Is found the combination
IF factors most favorable to ore depo-
sition and of evidences that such de- !
posits occur. Thorough prospecting
Of these two areas is certainly war
ranted by the favorable conditions of
structure. degree of metamorphism I
and general and special mineraliza-
ton. So far as the evidence at hand
goes, the chief values are to be expect
ed in gold and copper Considerable
promise is held out by many of the
better defined lodes. That portions Of
The mineralized shear zones in dia-
base may be found to constitute low
grade ore is indicated by the few as
says available Increase Of values in
fepth should in general not be ex-
oected for 1t appears that oxidation of
he lodes and shear zones has reached !,
! slight depth only and that secondary !,
Is absent. The Slate creek