Eureka daily sentinel. [volume] (Eureka, Nev.) 1871-1887, 1885-05-09
THEORY OF MINERAL VEINS.
Features of n ComstOck and
Steamboat Springs Compared.

Il chtures Oh the COmstOck anu
Steamboat Springs Compared.
Dan De guile, formerly Of the Virginia
Enterprise, is writing q series of articles
for the San Francisco Alta, and in the one
published last Sunday, in which he talks
OF the Comstock lode, he ventures the fol
lowing theory On the formation of mineral
veins: II is now conceded that the major
ity of mineral-bearing lodes are formed
either by sublimstion or ~infltration, very
few persons at present holding to the old
theory OF the injection of molten matters.
Hot mineral springs are important assist
ants, II not indispensable requisites, in the
formation Of mineral veins. At Steamboat
Springs, in Washoe Valley. the formation
of a large mineral vein is now undoubtedly
in progress. So slow is the process of for
nation, however, that to produce Q vein
such as the Comstock must have required
ages, almost beyond computation. At one
time, ages and ages ago, the hot water now
found at the depth Of from 1900 to 1000
feet undoubtedly reached the then surface
along the line of the lode. Ages ago the
subterranean fires and forces directly be-
meath and all about the Comstock were
undoubtedly much more active than at
present. The burnt and discolored hills
in various directions, particularly on the
east side of the lode in Flowery District
where were the latest vents for the heat,
heated vapors and hot water of regions be-
neath-still mark points where almost vol
canic activity once existed. Indeed, on
the west side of Mount Davidson and above
American Flat are to be seen the craters of
two extint volcanoes.
All lodes, however, have not been formed
in the same tanner. Not q few show that
they owe their existence principally to
aqueous solutions, while in others cyl
dences of condensations from sublima-
lions or gaseous emanations predomi-
nate. In great veins like the Comstock,
there are nearly always to be found proofs
Of the work of formation having been
performed at widely different times, as
well as through different agencies; aque-
GUS forces being at one time in ascendancy,
and the gaseous, with sublimations from
great heat, predominating at another. Be-
sides all this, all mineral lodes are sub
ject to transformation after formation.
Nearly all, therefore, have reached our
age after having passed through a variety
of influences. Aqueous deposits have
been changed by plutonic forces and de-
posits from sublimations by aqueous pre-
cipitations and infltrations.
To say nothing more about the forma-
tive processes, by means Of which the
Comstock lode was filled and mineralized,
ii is evident that some Of the causes
through which its production was effected
are still in operation; that it is still
{" alive and sensitive to wounding and
encroachment. The eternal fires beneath
the earth's crust are still active; heated
water is still being forced up and put in
circulation among the rocks as a solvent,
and the rocks themselves are kept at q
high temperature, which all chemists know
is favorable to condensation by crystalli-
cation. AS the machinery in the work
shops is still in operation, it must be that
some work is being done. The progress of
this work, however, may be SO slow as to
be almost imperceptible and incapable of
computation through measurement, unless
u special study of it should be made, ex-
tending over a great number of years
perhaps from generation to generation OF
man and age to age Of the earth.
But if we are unable to note and meas
ure the work accomplished in a given
number of years, we may readily find and
study the evidences that it is still in pro-
gress. The closing up of the ground
where openings are made and the cement
ing of materials loosely deposited in such
openings into q homogeneous mass, are
evidences that the heat of the water and
rocks, and the various carnations from
the bowels of the earth are still exerting
their procreant influences. The heated
waters are doubtless still dissolving out Of
the rocks their metalliferous contents and
depositing them in q more condensed form,
but the rate at which this deposition pro-
ceeds is SO slow that during the period
allotted as the life of man it would prob
ably not exceed in thickness q sheet Of
ordinary w~riting-paper.