Custer chronicle. [volume] (Custer City, Black Hills, D.T. [S.D.]) 1880-1890, 1885-12-12
The Mines Around Custer.
ALI MISUM.

ana ASSAY returns. ana IuTtneT more
these veins are neither small nor poor
in that metal but on the contrary are
large and rich. The development as yet
is meagre, but sufficient work has beer
done to show that the vein is at least *
feet across and extends Gas shown b,
the croppings) for at least one half mile
The strike of the vein is little north
of west and south of east, and the dip O
the vein is about 20 degrees from q
horizontal. 1T is walled and bounded
on the south by an immense dyke o
what we would call Il black gneissoit
granite, which here conforms to the
cleavage of the mica slate which is the
country rock The vein consists o
quartzite, made soft and partly decom
posed, and its texture in some degrees
changed apparently by the action OF
mineral waters, by which il has per
haps for ages been saturated. Tn,
theory by which We account for the
mineral in this character Of veins, based
upon what we know Of mineral, and our
observation of how these veins descend
into the earth, and deduced from years
Of study while working and sinking in
this class of veins, is as follows: First
that this quartzite must have been
originally deposited horizontally on the
Aanr nf nr lnl,n o;it
sand. We arrive at this from the fact
that it bears every evidence and has all
the markings Of stratatied rock, and il
found undisturbed and far away from
any dyke Of the SO called igneous rock
such as granite, porphyry or gneiss. this
formation would then be as barren OF
mineral As any other sand stone ledge
found in any non mineral country.
One reason for this conclusion is the
fact that there is sometimes wnat min
ers call horse found in the vein.
These horses are nothing but hard
places in the sandstone, around which
the mineral waters have passed without
being Observation-Disclosures places are al
ways barren of mineral. These mineral
waters must have come from d, kes oi
black granite which is evidently an
intrusion bursting up through the
sedimentary crust Of the earth, lifting il
and fitting it, especially where it is a
heavy strong strata as is found in this
case. which bends with the uplifting OF
the granite until it now lays Supported
by the granite, which diDs ~ shout al
angle of 20 degrees. These dykes OF
unStratafed rock are called by geolo-
gists igneous or fire made rocks and
this may 5c true IN one sense, but not
in a sense that they were ever molten
mass. The most advanced geologists Of
the present day are agreed that they
must have come up in a plastic state,
like mortar. Hot, no doubt, but no
more so than would naturally ~esult
from the friction Of Such a moving mass,
and the etfcrNescence arising from the
union of mineral waters, acid and aka
line, which are brought in contact. The
alkaline waters flowing and oozing from
feld-pathio dyke, carrying in solution
their mineral constituents. gold, silver
copper, lead, or aluminium, as the case
might hc, are absorbed by the quartzite
it being Of an acid nature, (all quartz
rocks are acid rocks the chemical
affinity would be strong, the natural
consequence of this meeting would be
the precipitation Of whatever mineral
these waters might contain. And thus
you find it in this case right here in this
quartzite which was once a sandstone
strata ofthe earth's crust but now chang
ed by the action Of mineral waters, and
also changed from it's original position
tY being upifted by this granite dyke
We haye dwelt longer on this branch
of the subject than We Intended, yet we
have done so knowing it will be OF
benefit to miners and prospectors who
are welded to the business and propose
to continue in it, and yet have had nc
chance to acquaint themselves with the
natural laws by which the mineral
kingdom is governed. And we do no,
pretend to have done so only IN part
But principle which we have tried
and always found to fit the case we give
as safe rule to work by. But to return
to the mineral of which we are treating
we presume there are not many of our
readers who are at all familiar with it
And yet we are told it is the most com.
mon Of all the minerals, as it is mixed
trample under foot. Still it is obscure
and scarce, because it is seldom found
in veins or bodies, but is generally
diffused through most every character
of rock and soil. 1t is however, a very
useful metal, and if found in quantity
"ill enter largely into general use II
has hitherto been applied in place OF
silver for plating watches, and for al
purposes where silver is used excep
money. 1t has about the same color
takes fine polish, and is very durable
IL il superior TO silver in many respects
AZ 1t is more dGctile, and although it il
next 10 the lightest metal known it ex
ceeds them all in tensile strength. 1t il