The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-10-09


them TO be deposited with the fine
mud rather than with the clean sand.
II these minerals came into the wa
terbody as sediments, they were
doubtless in an. exceedingly finely di-
vided condition, and In the sorting of
the materials by wave and current ac-
ton, would go into the mud instead Of
the coarser quartz sand, just as in the
lead and zinc go proportionately more
into the slime than into the sand. II
the lead and zinc salts were in solu-
tion in the waterbody, 1t would seem
would be much more favorable on the
mud flats than on the clean quartz
sandbars.
The Quartzite Rocks.
In the relatively pure quartzites and
ordinary sericitic quartzites, nearly all
the material is transparent in thin
section. Carbonate of iron Is widely
disseminated In these rocks and min
ute quantities Of lead and zinc in the
form of carbonates might occur with
the sderite and not be apparent un :.
der the micr ,scope. However, the
distribution Of the ore deposits leads
me to the conclusion that this Is not
the form in which lead and zinc may
be dffused in the rocks of the district.
The st. Regis, and In places the Burke
contains purple bands in which the
coloring matter as shown by Mr. CAL
kins, is hehatite. It may have been
precipitated as limonite from iron
carbonate and converted into hema-
lite during the regional metamorphism
Of the rocks. The same conditions
which precipitated the iron might have
precipltated lead and zinc salts. How
ever, the ore deposits can not be trac-
ed to the purple Burke and st. Regis
as source. The frequent association
of lead and zinc ores with limestones
might point to the calcareous Wallace
formation as the horizon of the pre-
sumed dffused naturalization, burt TO
this | have the same objection as
above. namely, that the distribution Of
the ore deposits emphatically pre-
cludes the Wallace calcareous shales,
limestones, and even the carbonaceous
argilltes from serious consideration
in this connection. The one formation
in the Occur d'Alene district which
does not seem open to any OF the
above objections is the Prichard ar
gillite. This contains opaque dust,
doubtless chiefly carbon. The forma-
ton is also characterized by the pres
ence Of considerable pyrite, which, In
it's present form, Is secondary to the
regional metmorphism, but in some
form was probably originally present
in the sediments. Mr. Calkins mem
lions also as accessory minerals rutile,
zircon, tourmaline, siderite. magnetic,
biotite, chlorite and a very small
amount of calcite. The two miner
ais which may be presumed to have
been originally present in the Prich-
ard mud and to have been capable OF
influencing the deposition of lead and
zinc sulphides, are carbon and iron
sulphides.
Metal Occurrence.
There is no very definite evidence Of
as wide diffusion of lead and zinc In
| the sedimentary as in the igneous
| " 10 VI. N
,olume before cited that L. Dieula-
| ait detected zinc in hundreds of sam
| oles of Jurassic limestone from central
s'rance; that j. B. Weems found by
analysis of nine samples an average
of O.O0326 per cent lead and O0Oo29
per cent zinc in limestones and dolo-
mites of the Dubuque region, Iowa;
that J. D. Robertson found in the Sill
| lrian limestones of Missouri lead up
to O.O00346 per cent and zinc up t.
l0.1536 per cent; and that A. NJ. Fin
layson secured similar results in his
study of the British lead and zinc de-
posts. 1t Is recognized that In all
these cases at least some of the diff
fused mineral may have been intro
duced in connection with the forma-
ton of the commercial ore deposits. II.
r. Balm argues that in the Wisconsin
| district the commercial ores have been
concentrated from diffused mineraliza :
ton that was deposited with the sedi-
ments because of the known absence
of igneous rocks of as late date as the
sedimentary beds, of the absence of
deep extending faults, of the presence
under the area of unbroken sheets Of
artesian water in sedimentary beds,
and of the sufficient evidence of the
origin of the ores by this agency G.
". Cox holds that "the Maquoketta
shale contains lead and zinc COM
pounds as original minerals" u.
Buckley thought that the ore depos-
It's which are found in the Mississin-
plan limestone In Missouri were con-
centrated from dffused deposits in
the Pennsylvania shale, limestone,
and coal. c. r. Van Hise expressed
the opinion that the lead and zinc sui
phides Of the Mississippi valley are
segregated from sulphides in limeS
stones. These sulphides were derived
from the sulphides of earlier rocks
which were probably transformed to
sulphates, transported to the sea. and
in the sea. as shown by r. G.. Cham