Custer weekly chronicle. [volume] (Custer City, S.D.) 1890-1931, 1898-12-24
Minerals Which Accompany Gold.


The following is an abstract of pa
per by L. A. Rickard read before Insti
tuition of Mining and Metallurgy, Ion
don, March, 1898:
"Tbe experience of certain mining
districts proves that gold is notably &c
companied by particular minerals. anG
this TO such an extent that they are con
sidered To assure the richness Of an ore
in which the gold itself cannot be visi
bly, discerLed These ''indictive min
erals" are not the same in every local
ity.
In Boulder county. Colorado, rosco
lite, Ia vanadlan nica) is closely associ.
ated with the tellurides of god. calve.
rite and sylyanite. The same rare min
eral is recognized in the telluride ores
of kalgoorie and West Australia. At
San Andreas, in California, uranium
ochre yellow oxide of uranium) distin.
guishss the pockets of specimen gold
ore to such All extent that it serves 70
guide in prospecting. In several parts
of Arizona, MANDATES of lead .ciarac-
terize ores rich in gold. and molly bdate
often accompanies the vanadium miner
ais and has been noticed in the ores OF
two celebrated lodes, the Comstock VI
Nevada, and the Vu.ture of Arizona
Crocoite or chIomate of lead character"
ICES several gold veins in Coolgardie
gold fields. In West Australia gold is
closely associated with tourmaline in
crystals in contact with coarse gold
The gold ores also Of Mysore in India
carry tourmaline.
These incidents, however, cannot be
trusted as reliable guides 10 gold There
are quite as many occurrences of a neg
ative kind. Zincblende, for example,
was quoted in one locality as a sure sign
of rich gold and silver. In West Aus
tralia, zinc forms the dividing line be-
tween rich and poor gold ore, but in
Arizona, the impoverishment of lodes
i'm depth, commences with an increasing
percentage of zIncblende.
again fuorite was observed as assoc
ciated with the telluride ores of both
Cripple Creek and Boulder, but in other
sections of Colorado the same tiuorite
is observed in connection with very poor
ores, and total absence of tellurides.
RhodocrOsite, the beautiful rose. colored
carbonate Of manganese cbaracteriZes
the rich ore at Rico but is a negligible
factor in certain lodes in Butte, Monta
ma. When calcite appears amid the
gold bearing quartz of California, it
means falling off in values, while at
Kalgoorlie it characteri1es ores rich in
telluride Of gold, and at Thuda in Trans
ylvania, very valuable gold vein has
been worked whose matrix was calcite
We are all familiar with mines IN which
pyrte is 50 Intimately associated with
gold that lessening of the one means
diminution Of the other, but there are
cases where an excessive percentage Of
pyrite comedies with impoverishment.
There are lodes in which the coarse
cubes of pyrites are less favorable to
the presence of gold than the finely
crystalline variety. There are also
those in which the reverse is true. Sim
ilarly. coarse galena has been supposed
AS less silver bearing than fine, but the
opposite frequently occurE.
When gold occurs in Dyrhotite ores
il is generally accompanied by small
percentage of copper pyrites. W lille
many veins carrying coarse gold incased
in white quartz persists to great depths.
gold quartz may be persistent when
wholly barren of the baser metals. Uni.
formity in the distribution of gold is
often an indirect evidence of the size of
body If gold ore. A patchy occur.
renee is less likely to indicate continuity
or size than homogeneity Samples
varying between narrow limits are more
encouraging than those which swing
between wide extremes.
IF We cannot accept the belief that
certain minerals ale indicative of the
plentiful occurrence of gold, what shall
be oaid OF the idea that they give an as
surance Of persistence in depth Thus
the finding of telurides in West Aus.
traIia in an ore, is generally considered
to permit the inference that the lode
will 20 down to great depth On the
other hand, the general experience with
telluride-bearingl lodes is their treacher
| Gus character as to permanence. The
combinations of tellurum with gold and
silver have proved of notable CONNER
cial importance in Pennsylvania, Colo
RADIO, and West Australia. There are
other districts where their occurrence
| is merely incidental in the process o
| mining gold ore. as in California, South
Dakota, New Zealand. In none of these
latter have they been indicative of any
specia, persistenc in the richness o.
the veins, and their occurrence has beer
merely an added obstacle to the success
FIJI extraction OF gold.
"In 1902, Klaproth discovered the
element of new process "tellurium" in
the ores OF Zalathna, and 80 led TO the
recognition oi large number of the
compounds of that metal with gold and
81 yer. Zalathna, Nagyag and Verstra
tax were gold mining centers WheI
1 -, ka nx.i,
of Dacia, and their very complex ores
have been a puzzle TO metallurgists o.
many generations. The veins penetrate
volcanic andesites and Tertiary lime
stones and conglomerates. This ancient
mining country shows today an example
of impoverishment in depth, while thu
refractory character of the ore has tried
the resources of the smelling establish.
ments of Schemnitz, Zalathna and Frei,
berg.
| I'm Colorado the tellurides were re-
cognized AS early as 1874 in Boulder
county. An experience Of twentytiv
years has proved that these ores occur
there in comparatively small hodies o
remarkable richness, but irregular and
uncertain. In Hinsdalc county and the
La Plata mountains rich telIurdes hayt
also been found and are at present being
worked. At Cripple Creek, the veins
penetrating complex OF volcanic rocks
have proved persistently rich to depth
of l 900 feet. In West Australia tel
hurdles are being mined in three locali.
| ties, and the wonderful DEVELOPMENT at
Kalgoorlie in particular has given a new
impulse to the whole industry of the
! COLONY. The compounds. however o
tellurium are far more widely dispersed
in gold ores than is generally supposed
The presence Of tellurides in the Kal
goorlie does not necessarily guarantee
persistent richness with depth. The
lodes vary in the amount oftelluridet
which they carry without a coinciden,