New Orleans daily crescent. [volume] ([New Orleans, La.]) 1851-1866, 1858-06-25


The whole history OF mining in other countries
suggests evidences favorable 70 the DOWNWARD contlu
/ uance Of our lead veins.
Mr.. Phillips, a very distinguished Engilsh oeolo
| giat remarks That, as general TACT, we cannon
doubt the far greater prevalence Of the mineral VEINS
\ ID the older than 10 the rocks Not one case
is known Of mineral vein being worked IN any part
Of the British Island above the new req stone ~
slight traces occnr but veins become abundant in the
mountain limestone, and in the older strata. But yet
/ ii is probable that this relation OF mineral veins to
the are 81 deposits Is merely consequence OF the
more general truth that their origin is from below,
/ and that the metallic and sparry matters which occur
| ns well as the issures which contain them, are more
/ abundant near the igneous rocks
/ Dale Owen, in his FIRST hasty Report on the Lead
Veins Of Iowa and Wisconsin, discusses the point at
some length. He says The lead ore in Iowa and
Wisconsin is mined in rock OF somewhat greater
antiquity than the mountain limestone which chiefly
furnished the lead Of England 1t behooves to re
member however, that the metallifer0us capacity oil
ROCKS depends not much upon their Theological cha
racter Thus thoue the lead bearing rocks England
and America are not strictly equivalent, they
aagous in these points which their prod1ctveness
chiefly depends. And SO far as difference OF age is
concerned. the advantage is with the lead bearing
rocks of America.
All other things being equal the older the rock
the nearer it approaches the inferior gneous rocks
the richer will it be in metals.
In point of fact, if we except the principal lead
region Of England Galena occurs far more richly
and frequently in formations older than the mountain
limestone ITSELF The lead mines of Spain are found
10 rocks as well as their own.
The lead glance veins Of Linares occur in granite
The c0lapa deposit of ore in the Sierra de Gador
which afforded ~ o00000 lbs. OF ore ia single year
is In limestone still older than ours So also the
well-known lead hills of Jamarkshier, in Scotland
In the mountains OF the Hortz, so rich in metallic
ores, lead occurs in immense veins in the transition
formation.
In Christianra, Norway, it occurs in mice slate
-E4l -. - ~ E-To
Sweden, it forms veins in primitive limestone.
AT Lozere, In France, granular and compact Ga.
lena runs through primary rocks and in Saxony il
occurs in the same position.
In fine, know OF hardly any lead region of i'm
portance on the European continent, which is moi
older than the mountain limestone Of England So
far then, the comparison of the geological character
Of the lead regions Of and other countries is
more favorable to those OF Iowa and Wisconsin than
ii the rocks had proved strictly identical.
There is condition OF things in the district on
which am reporting, which may be considered I'M
favorable to the prospects of mining country. 1t
is the absence of igneous rocks. mention this as
al exception TO a very general rule"
!" 1t is not says Phillips /" on account of the
great antiquity OF the slate of Cornwall that they
are very metsllifferous but on account of their
proximity to the granite. The rocks Of Ireland I'M
disturbed by any great axis, are very slightly metal
lifefous, while the same rocks when they have been
upheaved by igneous rocks from below abound in
metallic veins Of various kinds. There the most
general point Of view, in which veins present them
selves is in dependence upon the sources OF subter-
heat. In the rocks nearest these sources they
are most numerous and variable
But 1t must not be forgotten that this district has
been only hastily surveyed, and the mining thus fI
has been very superficial We must not conclude be-
cause no Happean or crystalline rocks have been
found that they do not exist there incline to the
belief, from the abundance of the metallic ores and
the rreguafity of the dip in the northern portion
Of the lead region, that the gneous rocks cannot be
far Cd.
The limited time allowed for the completion Of this
survey prevented from investigating the matter
as infinitely as could wish 1t is a subject however
which demands the most rigorous inquiry since in
the absence OF deep excavations, 1t is the most i'm
portant guide to the solution OF the problem Do the
veins of lead ore, after passing the blue fosserons
lime stone and undertaking sandstone, extend down
wards into the lower magnetism limestone n
1t Is worthy Of note in this connection that the
lead mines OF Missouri, which have proved SO rich
and productive, are principally in rock which is the
geological equivalent of our lower magnetism lime
stone.
On visiting these mines, was surprised to aud
them In rock resembling in physical character our
lower magnesium The observations of the Missouri
biologists have since proved them to be in that form
alton.
Dr. Little, Of the State geological survey. remarks
in bis able report Of 1865 The Galena is, SO far as
my knowledge extends, conferred to the magnetism
members OF the lower silnrian for formation" These
magnetism limestones are not, however, of the same
age as the galeniferons beds of Wisconsin , but as
may be seen by Or. Shnmards section, they lie below
the Trenton (bue) limestone, and are doubtless the
equivalent Of the calcferous sand rock OF the New
York biologists.
Il is thus that this lower magnetism limestone
is elsewhere lead bearing rock while we have also
numerous instances in which it has yielded consider.
able quantities OF lead at its out crop around the
northern border OF the lead region. These instances
shall notice particularly in my next article, and also
proceed to discuss the general principles which gov
ern the formation OF our lead veins