The Arizona copper camp., 1920-03-13
MINERALS OF BUTTE DISTRICT

peacock copper" 1t is found in cop
per veins of all ages and on all levels
and makes the "jewelry shop" which
occasionally delights the eye of the
shift-boss.
Chalcopyrite, the yellow copper ore,
is not as common as formerly. 1t is
practically unknown in the Anaconda
and Mt View mines, but is found as
mineral of the border zone of the
central copper area. In composition
it is about one third each of copper,
iron and sulphur 1t can be easily
told from the yellow iron-sulphur min
eral, pyrite, by it's softness, being cas-
liar greenish black powder. From
gold it is distinguished by its brittle
ness.
Tetrahedrite, the gray copper ore,
has Been found in small amounts in
nearly every mine in Butte. 1t is
about one-half copper, one-quarter an
bAAAO1AJ, anu OAC-4uCAIC II
frequently carries good gold and sill
yer values. Its cherry-red streak dis
tinguishes it from glance. If arsenic
occurs in the place of antimony the
mineral is called tennantite, and may
still pass as gray copper. 1t is quite
common in the northeastern part of
tho 6iCfrin w II 10 f011nd
gray glistening crystals coating the
walls of fractures.
From the foregoing description of
the copper minerals, the uninitiated
might get the impression that the ore
which goes to the smelters must be
very rich, and would expect to see
all these pretty minerals scattered
about the ore cars. To such person
the dull gray piles of rock which fill
the gondolas will he a sore disappoint-
ment. So we must explain that while
these minerals are found in the mines
and while the total copper produced
is enormous, one must remember that
the great bulk of the ore consists of
tiny particles of valuable minerals
scattered through quartz and altered
granite; that in mining, much waste
rock is inevitably broken with the ore,
and that the wheat and the chaff''
must be shipped together to the con-
centrator for further treatment.
The Butte camp has produced over
300 million ounces of silver and one
might expect to find here a large
number of the silver minerals. But
such is not the case, as will be under
stood when one is told that the ore
runs less than two ounces to the ton,
in the copper veins of the district
Trying to see two ounces OF silver
specks in a ton of rock would be
worse than hunting for the proverbial
needle in the hay stack So we turn
that problem over to the metallurgists
at Anaconda and Great Falls. How.
ever, an occasional specimen of native
silver is found, and the silver sulphide
argentite has been noted. Undoubt-
edly the silver exists also in various
combinations with sulphur, arsenic
and antimony, but occurring in very
minute specks. The zinc ores con-
tain nearly three times as much sill
yer as the copper ores.
Gold, which runs from fifteen to
thirty cents per ton of ore, is even
harder to see than silver. Some of it
probably occurs in native gold. Some
of it doubtless is combined with sill
yer, tellurium and selenium to form
tellurides and selenides. This is as
sumed because of the tellurium and
selenium detected in the electrolytic
refinery at Great Falls.
The 10000 tons or more of zinc
which is produced annually comes
from the mineral sphalerite. This
mineral locally is called zinc" by the
miner, but it IS really only two-thirds
zinc, the remainder, being sulphur.
Many good MINER has been deceived
ty this mineral and will be interested
to know that the name "sphalerite"
comes fro ma Greek word meaning
treacherous, and that the word
"blende" which is sometimes used,
comes from a German word meaning