The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1912-03-14
GEOLOGY Of THE ORE ZONE
Report on the Wardner, Big Creek and
Placer Creek Ore Zones by
Chas. F. Ruddy.
Wallace, Idaho, March 13, 1912.

Wallace, Idaho March 13 1912.
In order to write report of any mining property that will
be comprehensive to persons not familiar with the geology 0f
the district i'll which the property situated the first essential
is to give clear account of the prevailing geological
dons of the particular property and comparison the
only of value becomes necessary to give descrp
ton also of the district and of the producing mines thereof
showing the relation of the shoots and neghborng
rock strata that may posulae that where all geological
conditions the to the extent of surface and develop
ment exposures the unexposed underground conditions will
also be alike
The mineral bearing rocks of the Occur Alene mining dis
c the oldest of sedmentay strata and belong to the
Azo period of the earth life and recognized by the total
absence of fossils. f. L. Rasome and r. G. Cakins of the T.
IS geological survey have divided the scdmentation into five
distinct strata each having distinct structure and composition
but grading into each other gently to show distinct
line of demacato These strata have been named as TO
connect them with the part of the district where that partc
lar strata prevail
The oldest strata of which there is any exposure ls an
argacous mud slate of thickness Of about 6o0o feet the
upper portion of which mixed with considerable quantity
Of iron and siIcous matter IS
This being the prevailing rock of the Priclard creek basin
lis called the Prcard slate The next everything rocks named
the Burke quarze because Of large OF it near the
lvage of that composed OF graysh green quartzite
mixed with subordinate quantities of the Pritclard formation
and has aggy structure throughout The thickness OF tins
strata is about 2OO0 feet.
The next strata above the Burke is the Revett quartzte
This is white qrartzte spotted with yeowisl brown specks
IF sderte and ntesrate with subordinate mcaceous sand
tone and has a thickness of about 1900 feet
Above the Revet strata is the ST. Regis which much like
the Burke being greensb purple quarze with small amount
If iron and nagnesa, giving shaly structure, the thickness
If which is 1000 feet. ~
The next strata everything known as the Wallace and is
he latest and youngest of the sedmentares OF the known
mnerazed portion of the district This strata comprises
of the exposures Of the South Fork water
hed has thickness variously estimated from 3OOO TO oo
feet The composition Of this strata is quite different from
ter of the Others being mostly cacareous shale inerbed
I'd with dolonc sandstone and bands Of light gray quartzte
quite faggy and of yellow and purple coors ms
strata is easily eroded making fertile soil which supports
heavy growth of vegetation.
These strata descriptions taken from geology and
deposits of the Occur Aencs page 2 Professional Paper
No. g. u S. Geological Survey by Ransome and Calkns
The Coeur Aene mining district which has produced IN
ound numbers $25O000O0O worth of the of silver lead
oppcr zinc gold and small quantity of antimony Ninety
per cent of this amount from the watershed OF
the South Fork of the Cocur Aene river fths of which
produced from the sheaed quartze of deposits
yng on the south side of said river and enclosed within the
boundaries of the Big Creek and Placer creek faults WHICH
their eastern axis their point of conveyance near the
oks of Placer creek and their western whore they meet
The great Osbrn fault west of Wardner thus showing this
mnerazed zone to be entcuar fault block filed with minor
faults the result of shcarng The Placer creek fault which
constitutes the hanging wall ssure of the zone is filled
with geous dabase dyke considered by the government
and other eminent authorities whom have viewed to be the
genesis the deposits Of the ncghborng quartzltes by
replacement process and deposited out of the circulating min
eraizers ga vapors and thermal waters emanatng from
the dyke magma 1t also probable that the energy of the
dyke will for the ng assuring and shearng OF the
fault block This fault block is composed almost entirely OF
eve quarzte the ovcrng strata of Wallace and St. Regis
having been removed by strain caused by the uphu Of the
Reve rocks.
The district is divided into two nearly equal parts by the
great Osburn fault that extends east and west direction for
its entire length and shows drop of the strata of the south
half of from 5000 5000 feet which includes the fault block
above described.
The Reve rocks the most homogeneous Of the district
and being purely scous and being fractured are
more conducive of deposition than the other strata for the
that being nearly free from argacous matter there
are no dams formed that interfere with the free circul-
ton of the mnerazes causing great uncertainty Of ore de
position
For of space the entire report of the interesting fore