Buchanan County bulletin and guardian. (Independence, Iowa) 1866-1869, 1867-07-26
THE DUnUQUE LEAD MINES.
Report Of tie STATE Geotogist upon Them.
Iowa CRY, July IL, 1861.

La the course Of the chemical invesliga-
tions for the geological survey, it was found
that there were number Of subjects con
nected with the inineralogy Of the lead region
Of Iowa which had hitherto received little or
10 attention.
This omission was partly 10 consequence
Of the expectation on the par. Of the former
chemist that the work would he completed
.. future time, and partly because subse,
quent advancement in such Investigations
has made the importance Of some ef these
subjects m re apparent.
Our late visit 10 Dubuque vas made for
the purpose Of collecting data and material
to supply as far as possible such deficiencies,
and In some respects it was quite success
fal.
Some Of these results have now definite
practical value, bu. other, at preseu, on in
teresting scientific facts, yet We do not know
how soon they may assume n practical i'm.
portance. Among the interesting facts
which we obtained there, are several that
have long been known 10 the mners, bu,
have never been published 30 the world We
are apt to forget that scientific knowledge !.
oaly the knowledge Of the few collected, ar
ranged, sysiematiErd and published for the
benefit OF all, rad that the knowledge Of the
miner differs from that Of the rnineralogst
only in degree, no, in kind.
Capt. Thomas Leyir.s, an old aid exrer-
fenced miner OF Dubuque, Who furnished
much valuable information for the former
geological report also first called our a,ten-
lion to the we'll marked physical difference
beiwee II the lead ore Of the eas.-and west,
and the north. and-s south lodes. This differs
ence is easily recognized by any person af.
ter his attention has been called TO it and
the fact is q very interesting one, yet it has
never appeared in print before, so far as we
are aware. Prof. Heinrichs is giving this
matter ts merted attention. and hopes to
derive some hints from it concerning the rel.
ativs difference in the age Of the two sys>
TENS Of crevices or lodes.
Mr.. r. Simpson, Of Rockdale Smelling
Works, also called our attention to a grey
substance Of ore obtained from q limited
part OF one of the mines near Dubuque which
he finds TO greatly resard the process OF
smelling. and to diminish the product Of
lead. We subsequently obtained good spec
linens Ut this ore at the mine, and the pros
lessor has already made some analysis of the
substances referred to which he finds to be
carbonate Of lead--the same in composition
~ the grey substance often found coating
the common ore. Iu this case, however, it
is disseminated throughout the mass Of the
ore, the small cavities of which are often
filed With crystals Of the same substance.
The carbonate Of lead when obtained in suf.
fcient quantities is an excellent ore If smelt-
ed in suitable manner, but the process in
use for this common (the sulphure,) ~ not
suitable for the carbonate, aud the presence
Of the latter with the common ore, seems to
be worse than useless.
This arises from the fact that the carbon>
ate fuses Il much lower temperature, flow.
ing over the latter ore in the furnace, and
prevents the combustion Of the sulphur which
it contains and the subsequent liberation Of
the lead.
The only modification ct the process of
smelling this mixed ore--that is the COM
mon process-is to add small quantities Of
crushed charcoal at frequent intervals du>
ring the smelling, and even this, be thinks
Of dcabtful value.
It seems improbable tha, large quantities
OF these mixed ores will be obtained. and
furthermore it is reasonable to expee. tha.
the grey Stag obtained in smelling it. will
contain more than the usual quantity of
" Stag Lead which will be saved BY the Sec
ond smelling, and the aggregate product
may these not fall so far short as the dimin>
ished product Of the first smelling would
seem to indicate.
From the smelling works before mention.
cd we(kained specimens, illustrating every
stage of the processes of washing and snelt>
ing, including the sediment from the troughs,
the different slags from the furnace, and
both soft" and Stag" lead.
All these will be carefully analyzed and
the results given to the public, together with
such suggestions as may be deemed OF in>
terest.
We also obtained specimens Of quite
number of other mineral substances which
are usually associated with the lead ore.
From these, and from examination of the
cabinets Of several citizens of Dubuque,
Prot. Heinrichs was able to make out the
order OF occurrence Of nearly . dozen differ.
ent minerals, or to be more explicit, it is
known for instance, that a certain mineral is
found in crystalired form upon the surface
Of the rock, aud that upon the latter. erys-
tails OF another mineral will be found. and
still others upon the last, etc. Il is this or
der Of occurrence Of the different minerals
which is in part engaging the Professors at
tent:on.
Ii was also our intention to obtain stats>
teal information in relation to the present
and past product Of the mines,-but we found
that perfectly reliable statistics Of this kiud
were very difficult to obtain. Indeed the
Oldest and bes informed mining ard smel,.
ing proprie,ors were slow to give definite
opinion upon this subject, although they
we're very willing to comply with our wishes
in this respect far as possible. From con-
versation with these gentlemen l obtained
the following impressions, namely, that lead
mining is now in tolerably prosperous con.
dition, but that there were times in its early
history. " hen more or less was raised per
man, than now. The increased price in lead
makes mining Us prof able now, as it ever
WAS, although it requires greater proper.
ton of labor and skill TO obtain the ore than
formerly.
Little or no change has taken place in the
methods of either mining or smelling fos 20
wears, except the projected drainage o. the
mines by means of adit levels.
An enterprise of this latter kind has been
in progress for couple Of years By New
York company, and promises to be very sue
cesssul. 4 large area will be drained by
this level. when completed. which experien,
ced miners believe will Weld large amounts
of lead ore. which are now inaccessible ON
account Of the water.
Should this enterprise succeed, there are
other regions near Dubuque which may be
drained in the same manner, with equally
good prospects OF success.
A new era in the history Of Iowa lead mi
ming evidently depends upon the success or
failure of the company now operating.
Up to the prcsen. time there are no indi-
cations that deeper mining will be proti,a.
Bile, or indeed in any degree productive. The
thickness Of the Galena limestone in the VIZ
cnity Of Dubuque is about two hundred and
fifty feet, and the principal portion Of til.
lead ore is found above the middle Of il, very
little being found near its base or top.
The only exception to the latter, known to
me, is shown in an opening rccently made
short distance from the city by Messrs. Me.
Craney 4 Hickock. Here these gentlemen
have found lead bearing crevice in the ex
treme upper part Of the Galena limestone.
which has no cap rock, the shaes Ct the So
called Hudson river group lying immediate
ly upon the top of the tissure. What the ex-
tent Of this deposit OF ore is, remains 10 be
proven, as it has only been opened few
Has nE I>.I