Lyon County times. [volume] (Silver City, Nev.) 1874-1907, 1906-12-15
TESTING FOR COPPER.

Copper-sp. or. 8.84-occurs native
and in the form of many ores, nearly
all of which are highly colored and char
acteristic.
Any copper ore wetted with a little
acid will put a copper film OIL a knife
blade rubbed on it.
Copper ores, boiled with nitric acid,
give greenish solution; and ammonia
added to this produces fine deep blue
color which is unmistakable An ap-
proximate idea of the amount of copper
in rock may be had by this test in
camp. Take as much ore-pounded fine
as will rest on a dime, boil this
amount i'll about teaspoonful of nitric
acid, after cooling add ammonia till the
acid is killed, then add water so as to
fill tumbler. By comparing the depth
of color with that of a known ore the
percentage of copper in the solution may
be pretty well guessed at.
With the blow pipe copper ores give a
green flame, with soda on charcoal they
fuse and give bead of copper.
Copper occurs mostly in contact veins
and distributed in patches in strata in
the neighborhood of veins In places
large bodies of copper occur-quite If
regular but generally connected with the
vein by stringers of ore, sometimes only
a fraction of an inch wide.
Copper is precipitated most readily in
limestone strata, or strata containing a
good percentage of lime in their compo-
sition. Very many copper bodies are
in the form of conglomerate, and the
copper in these is very unevenly dis
tributed.
A favorite contact for copper veins is
that of lime-carrying stratum with
some eruptive rock, so that copper is
not uncommon in some metamorphosed
schists and states, in countries of trap
dykes.
The ores of copper are numerous, but
the chief are the following:
Cuprite-Oxide of copper 81 per cent
copper, sp. or. 6-hardness a. 1t is
cochineal red with brown scratch. 1t
is the richest copper ore and runs with a
green malachite.
Melaconite-oxide of copper-S0 per
cent copper, sp. gr. 6.2, hardness 8,
color black and scratch black. 1t may
be mistaken for manganese by the fact
that the ore will blacken the fingers.
Redruthite-copper glance 70 per
cent copper, sp. or. SIS, hardness 3.
Black and easily divided up with knife;
scratch black.
Covelite sulphide of copper-sp. gr.
4, hardness IL. Blackish blue in
color, scratch black; 66 per cent copper.
Malachite carbonate of copper SIS
per cent copper-sp. or. 4, hardness 3
4; color green and scratch green.
Azurite- carbonate of copper---55 per
cent copper, sp. or. 3.S, hardness Sd.
Color azure blue, scratch blue.
Bornite-- -sulphide of copper and iron
SIS per cent copper, sp. gr. 5, hardness
3, purply black in color, scratch black.
Crystals of bornite are purple.
Chalcopyrite sulphide of copper and
iron---34 per cent copper, known as pea
cock ore. SIP. gr. 4, hardness 3---4, iri-
descent, scratch greenish black.
Neutrality-suspicious. of copper---45
per cent copper---sp. .sgr. 7.3, hardness
3, dark green, scratch olive green, gen
orally more or less fibrous.
Chrysocolla---s ilicate of copper-37 per
cent copper sp. gr, %, hardness 2-3,
blush green, scratch green, often occurs
as scale or coating OF other copper ores.
Besides the above there are several
ores of copper with arsenic, anthony
and iron, some with very high percent
ages of copper. All copper ores can be
very easily known by the acid and am
monia tests and the coppering of a
knife blade. Ammonia colors an acid
solution of nickel blue, so where there
is any doubt, the knife blade test should
be made as we'll as the ammonia test
Los Angeles Mining Review.