Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1896-07-18
The Mines of Demereau Mountain.

elaborate report upon the mines of
Demereau Mountain, recently written
by our fellow townsman Mr.. C. w. Rob-
bins, which We cheerfuliy publish for The
benefit Of our many readers who take
an interest in the development of the
different enterprises in the several
mining district by which Custer City is
SO happily surrounded:
Demereau Mountain is situated about
one mile distant in southeasterly di-
rection from the town of Pringle, Custer
county, ;. ID. Pringle is small village
the B. & NJ. X. r., IL miles south Of
Custer. On the older maps of the Black
Hills it will be found designated as
Point Of Rocks" This has reference
to the nigh granite promontory which
|jnts out so abruptly where il has been
|cut through by the rapid current Of
Beaver creek, which flows in an easterly
direction to Buffalo Gap, in the foot
Ing into the south fork Of the Cheyenne
river. The ummit of Demereau Noun
tain rises to an elevation of about 1000
sCGb NDosC rNo ANNNl. Oh viz NtSl
side slopes down 10 a beautiful park like
valley, watered by many springs and
brooks. The valley of Pringle is sur
rounded on all sides by mountains, but
my reason for selecting this one for
particular description, is because it is
full Of mineral veins.
These veins are for the most part
easily traced, as the formation in which
they are found is so varied that il gives
the whole mountain where the rock in
place is exposed a striped appearance.
The veins are also varied in the char
acter of mineral they carry, copper is
found in some Of them, lead and silver
in others, and in some cases, traces Of
nickle and tin. Gold is found in all Of
these veins, sometimes occurring in
quartzite, some times in large veins Of
pure quartz, sometimes in a conglomer-
ate of mingled quartz and feldspar, with
much iron, limonite and hemetite, and
often heavy Gaping Of black carbon
ate of iron.
The country rocl is the "Archean" or
old micacious slate, which in some
places has become so impregnated with
iron oxide as to form quite extensive
beds Of mineral paint. This paint, to
gether with the iron it contains, carries
a small per cent Of copper and from
81 to So in gold per ton.
The igneous rock is granite Of the
coarsely chrystaline variety, which runs
through the mountain from north to
south. These granite dykes are eviden,-
ly intrusive, having pushed their way
up through, not only the states, but the
Potsdam sandstone, and even piercing
the limestone, which is The topmost
strata Of the sedimentary rocks that are
found still remaining as a Gaping to
many Of our most elevated peaks in the
southern Hills. On the Demereau
mountain these granite reefs are gener-
ally quite narrow, dividing the veins OF
mineral, and forming the walls, either
foot or hanging, while the opposite wall
is usually slate, or as in many cases, a
BLACK hornblendic schist. The veins. so
far as they have been prospected, or
opened, are all vertical. Although 1t Is
possible and highly probable, that there
{willxse found fiat pay chutes in nnsps-eee,
y&txe siiiceous belt of the Bald NO
! tain district in the northern Hills, web
| of Deadwood. | would say TO miners
and others, who desire to prospect fol
! the precious metals in this vicinity that
north, south, east and west, the noun
| tains have never to my knowledge fel!
| the point Of a pick. The field is wide,
| and il is open, but Demereau mountain
| itself is captured. 1t is covered by q
group of 81 quartz locations and water
| rights. These u claims contain more
| than 81 prospect holes, and some of
them are shafts more than 40 feet in
| depth. Each shaft or opening discloses
/ a vertical vein Of mineral, with a very
slight dip TO the east. These veins vary
| in size from 3 TO 10 feet in width, and
every one thus far tested assays well in
gold Some ASSAYS of exceptional high
grade have from time to time been OBJ
taired, while the general average taken
collectively exceeds in richness and
uniformity, and considering the present
meagre development, any group of like
extent and magnitude which l have
examined, or with which am familiar.
This is putting it quite strong, and lest
my opportunity for judging might be
called in question, will say that l have
mined and prospected for the last 20
years in different districts, and in addi-
ton 10 which. my duties as collector
and representative of the mines Of the
Black Hills at the great mineral exhibit
at Denver, Col, in 1882, and again as
collector of Black Hills minerals (which
il was my duty to have tested for the
Worlds fair in Chicago in 1898, should
Justify me in claiming an experience in
these districts not exceeded by any one,
and amply sufficient to form basis for
nav statement. If there is any mistake
il rests with the assayers, residents of
the Hills and elsewhere, whose reputa-
.tions are above reproach. hold by the
score their certificates still, and their
records vill show that l have told the
truth. The following taken from aver
age samples there are no specimens)
| from claims all oyer the mountain. will
| be sufficient to show how they run:
n orp vrN