El Paso herald. (El Paso, Tex.) 1901-1931, 1912-11-02
Western Side of Peloncillo
Range, South Of Stems,
Has Mucn Low Grade Ore

Constantly the area Of the copper
belts of the southwest is being ex-
tended by new discoveries. A recent
trip through the western part of New
Mexico into the eastern part OF Art
IONA impressed me as disclosing a re-
gion which viii in the future figure
prominently IN copper production, al
though it seems to have been over
looked by the earlier prOspectOrs,
whose whole efforts were directed to
the exploration for silver and gold.
Reference is made particularly to the
western side of the PelOncillO range
south of Stems, New Mexico While
there is one old mine there, with a
record Of important production, 1t be-
longs to the vein class OF ore deposits
which in former days was the only
class of mines that attracted the pros
pectOrs. 1t is the Johnny Bull copper
mine. To the modern prOspectOr, how
ever, there is every evidence Of extern
sive copper deposits in the class called
disseminated copper deposits which
will in the long run prove Of great
economic Importance and viii over
shadow the vein deposits
An authority, 3. S Butler, says that
from the standpoint Of mineral COM
position and geological occurrence, the
copper deposits may be grouped into
six principal classes and the approx
mate quantity derived from each
group may be ascertained. In a gen
eral way this grouping also classifies
the ores according to the metalurgical
treatment to which. they are best
adapted.
Important Belt in san Simon District.
There is an important belt of dis
seminated copper deposits in the Pc
lOncillO mountains IN what is called
the san Simon mining district, which
begins a few miles south and south
west of Stems station on the Southern
Pacific dailrOad in western Grant
county. New Mexico, and extends
southwark some miles. Prominent in
this belt are the group OF mines called
the King and Queen copper mines and
the Johnny Bull mine. which are about
nine miles south of Stems, lying on
the western slope of the range
The immediate region of these min
ing properties and in which they are
located, is composed Of both stratified
and eruptiVe rocks CarboniferOus
limestone attains great thickness and
thin strata OF shale and slate are in
terbedded at particular points in the
limestone series. Two principal erUp-
tive rocks broke through the sedt-
mentary series, disturbing and fitting
them. forming intrusive bikes and eX-
tensive surface flows. The older of
these pOrphyries is basic in character
and dark colOred and is perhaps
augite-andesite The newer pOrphyry
is Of more acidicr character, light in
porphyry. It is this later eruptive
rock that forms the intrusive qUarzose
bikes that penetrate the limestone
and the earlier audesite flows.
The intrusion of these acidic bikes
into the basic compOnents is the direct
cause of the induced naturalization,
says Fayette A. Jones, the mining
geolOgist The effect of metamOr-
phism is observed near and along the
planes of contact of the bikes with the
limestone and the andesite. Much of
the limestone has been altered into
marble and massive garnet rock, eX-
tending over the zones of mineraliza-
ton. EpidOte is also abundant and
exists throughout the entire range Of
the mountains.
The usual occurrences Of the va
riOus ores Of the Peloncillo range are:
First, gold and silver occurrences
along the contact of the acidic intru-
sives with the basic andesites; second,
lead-silver deposits in the limestones,
occurring in chambers erOded by the
action of water in and along fault
planes; third, copper-silver segrega-
tons along fault planes, near the con-
tact with the intrusive rocks; fourth,
disseminate copper sulphides through