The Neihart herald. [volume] (Neihart, Mont.) 1890-1901, 1892-06-11
GENESIS OF ORE DEPOSITS.

favorite theory and is sure he can
support it by facts and arguments
from facts. the diversity of opinion
is such as to create a certain degree
Of doubt as to the worth of scientific
light upon such questions. But
lately has come before our ooserva-
ton the following paper written by
Theo. B. Comstock, Director OF the
School of Mines at Tucson, Arizona.
He speaks of assure and of contact
veins and ascribes scientific causes
to their peculiar formations. The
ore-leads of the Little Belt Mount
aims are similar to those described IN
the paper:
Gin these days of hasty conclusions
and the overcrowding of scientific
literature with opinions and half-de-
yeloped theories, it is refreshing to
run across an occasional example of
undue modesty in presenting the re-
suits of elaborate experimentation.
NV excuse for thus tardily calling
attention to a marked case of this
character, entirely without the know
ledUe of the author. is the conviction
that the gentleman himself will not
Law claim to full credit for the work
which he has planned and executed
in a thoroughly scientific manner.
Especially does this action seem fit
ting as preliminary to an extension
of the same Investigations by the
present writer in the metallurgical
laboratory of the Arizona School of
Mines. In fact, it is only just to
confess that the inspiration of these
last experiments, for which prepara-
tons are TO- being made, came ORR
ginally and wholly from the most in
teresting results of Prof. Won Streer-
uwitz's patient and intelligent OBJ
~servations in his laboratory at Hous-
ton, Texas.
In the paper quoted, Prof. Won
Streeruwitz does not make very
clear how much of the value of his
well-fortified conclusions rests upon
the skill with which he has himself
conceived and executed a most con-
vincing series Of experiments. But
those who have seen some OF the
tubes with miniature veins of gold
silver, copper, lead, ETC., and Others
with beautifully formed agates, need
only the concise reasoning of the ar
ticle referred to, in order to under
stand the originality, perseverance
and devotion to truth with which thu
investigation has been carried on
through several years of diligent ex
perimentation. In the language 0
our author, the experiments would
so far, appear to establish the follow
ing points, viz:
l. 1t is principally the iron which
in silico-ferruginous assure veins
from greater to (by mining) a%ccessi
bic depths.
2. More silicious ore-leads, carry
ing also large quantities of iron ano
having silico-ferruginous outcrops
seem to be deposited from hot aque.
Gus solutions of the metals and sill.
Gates.
}. Metals and metal combinations
contained in the rock surrounding
the assures and crevices were proba-
bly, leached out by the hot liquids
contained in the assures and precipi-
tated on and combined with the sill
ceous iron growing up in the assures
4. The assures could be charged
with ore-veins in a comparatively
short time, since, no doubt, high tenn
perature and galvanic currents ex.
listed in the assures at the time o.
formation of the ore-gangues.
.. In contact-gangues the preci
pitation and disposition of ores wa
materially facilitated by galvani'
currents caused by the contact o
different rocks, and it is owing t.
the prevalence of galvanic current
that in most cases richer deposits a
the intersection of two or more lead
we're formed.
6. The so-called iron OUTFLOW
e"gossan," "eiserner hut" "Pacos,
"Colorados," ETC. are frequently nc
the product of igneous eruption, bu
deposition product from aqueou
solutions: and alterations in th
rocks contiguous to such OUTFLOW
are not necessarily the result
eruptive agencies, but of a leachin
process.
7. The formation of banded ae
ates does not always take place, 8
is generally believed, in the %cavitie
of rock, but can also occur free i
solutions; and the thickness of tn
bands progresses from the cente
outwards, although a reverse process
by osmosis may be possible undf
1871 ooxol,