The republic. [volume] (Washington [D.C.]) 1849-1853, 1850-02-13
Mining ON Lake superior.

We gather the following facts from the synoosis
OF the results OF the exploration of the U. s. Geo
logical Corps, in the northern Peninsula of Mchi-
gan, under the direction Of j. w. Foster and T.
ID. Whitney, contained in the New York T,iLune',
Washington correspondence. 1t is addressed to
Hon. Justin Butterfeld, Commissioner Of the Cen
eral Land Once IL Is attached to list of the sec
tions OF mineral lands between Portage lake and
the Montreal river, near Keweenaw Point, and in
Isle Royale also the tracts contaning iron between
Chocolate river and Keweenaw bay. Four geolo-
gcal maps accompany the exploration, embracing
the above regions.
The geologists have designated as mineral lands
tracts supposed TO contain copper, sometimes
ciated with silver
Experience" they tell us, .sin mining and the
examination of a great number of localities have
demonstrated that the veins of copper and Its ores
In sandstone and congomerate are not to be relied
on, and that when worked, 10 an inconsdera.
bie depth, they give out" As all the productive
lodes are confined to the ranges of trap, all the
mineral tracts designated by Mcssrs. +. and w lie
within those ranges. The trap ranges consist of
a belt of igneous rocks. chiefly horneblende and
ieidspar and extends from the Montreal river, dis
appearing IN the lake at the extremity Of Kewee-
nav Point--its course is north of east, width two
miles 70 twelve, and length $50 miles "Copper
mostly native, is disseminated, but more profuscly
In some places than In others. In fact, there may
be said to exist two centres Of metallic riches
around each Of which copper has been accumulated
IN considerable quantities-the one (the Keweenaw
Point centre) has system OF veins cutting across
tue Trap range, anu within this System included
the Chf, North American, North West, North
Western, and Copper Falls mines."
The other they designate as the Ontonagon Cen
IRE, the veins preserving parallelism with the
range, or running with the formation in this .vs
tenn they include the Minnesota, the Ontons gon
and the Ohio Trap Rock mines. Some of tbese M. .
cunuations OF copper mere beds the result of
segregation, while others contained In 6ssure.
formed subsequent TO the containing rock and as
ISOLATED with venstone entirely dissimilar The
copper bearing rocks form two independent rrouns
with distinctly marked peculiarities. Over Ia rge
portion OF the area examined tho rocks are con
ccaied by accumulations of transported matter
sucn as SAND and clay bearing trces--losses cover
tne humid ground like a carpct-snd il is difficult
TO trace boundaries. The most productive lodes
rarely exceed two feet in width, and a long tir,o
must elapse before 1.-THE Of the mineral wualt ~
this region can be revealed. The testing Of ..;r. !.
- a heavy item of expenditure The Corn,,,u
miners spent 500 000 in twenty wears IN J;ro,
ering veins; and their underground uncr,tion.
sinking and driving. extended To sixty three miles
To designate those tracts only That contained
productive veins would, therefore, have been i'm
pos le ''s" iin
In the metallic character of the veins in Isle
hoyale, the goologists have but little confidence
Durlns the past season, says the report, the min.
ing operations In this region have been highly sue
cessiul. About 200 tons OF copper have hecn
shipped, mostly IN masses nearly pure Nearly 600
IONS OF copper have this season been shipped from
,ne Chn mine, which shows no signs of exhaustion
Inc copper yielded about 80 per cent of pure
metal. They think that the Minnesota mine bids
iair TO rival the Cliff mine in richness and esti
mate 600 tons, or 4,0OO,0 900 pounds as fie proba
bic product Of the Lake Superior mines in Is50.
Detroit Adreriissr