New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1868-08-05

ties of the lead he is working and can tell at once
whether rock is granite, or first or second class
quartz This requires considerable practical eXpe-
rience. l have seen gold quartz of every
conceivable color and fOrmatiOn-white crystal cold
gray all shades of blue, yellow and pink, and every
shade of dark to Jet black. Quartz is usually very
| rich when gold can be detected in it with the
naked eve. Miners understand what partlcu-
lar formations carry the gold and they seldom err ~
estimating It's value In sulphuIets the IRON VIII
glisten with brlancy that makes any ineXpe-
IienCed observer pronounce it gold but the gold is
infused III the iron in very fine particles, ana seldom
can be seen at all Occasionally nugget gold VIII be
found in quartz bnt il is only in specimens OF
uncommon richness that the gold appears III that
way. The average cost of mining ore IN COLORADO
wOnld estimate at 81 per tun In Montana IL C0stS
probably IS per tun, but it's development Will be
4 cheapeued as il is systematlZed. .. -,
! When the ore is mined ii is delivered to the mil
either by wagons or railways where IL IS broken
about as fine as stone is usually broken on good
turnpike road. This is sometimes done by machine
called " cracker" but usually by hand, with the
common sedge. Ii is then ready for crushing, ana
the process in most general use is the stamp mill
mill consists of from two TO SIX batteries, each
battery having FIVE stamps, which consist OF heaVy,
round bars of iron, set perpendicuarly widening at
the bottom, on which is fitted steel shoe Beheath
the shoe is steel die firmly imbedded on which the
stamp drops 1t is hoisted by each revolution OF the
machinery to a certain point, whlred partly around
ms il HOSTS and its force consists simply IN the drop
of its weight upon the die. Each battery IS sur
rounded with an iron frame or box, into when the
ore is thrown, and strong stream of water pours
| constantly On the outer side OF the battery
a screen or sieve issues the water and WIN
| it is carried the fine quartz as III
is pulverized so that feeding goes constantly TO
supply the place of the fine quartz as II escapes In
the battery is placed quantity of quicksilver, win
which large proportion of the gold amalganates
as the rock is crushed and is held there until the
" cleanup" Many particles of the gold. however,
escape with the fine quartz through the screen De-
fore il is brought in contact with the mercury ana
in order TO catch it, the water and quartz from the
latter run over copper plates from two to four
feet wide and ten TO twenty In length, amagamated
81 fla,t afa 10
every particle of free gold will reach the bed of the
plate in passing it, and safely lodge in the mer-
curry but i the gold is mprsgnaed with ,v the
| the mercury. 1t will pass over the plates
and sink in the boxes rppes (such as are used IN
gulch mining, and before descrlbed While the light
earth and sand viii wash away These mixtures OF
gold with the base metals are called sulphurets, and
they worked successfully in Montana thus far by
arastras barrels An arastra is simply carefully
laid bed of stone about eight ten feet IN diameter
encircled with wooden rim an upright shaft stands
i'm the center with two arms extending ont, TO each
of which is attached heavy rock with q smooth
under face 1t is so attached to be raised little
in front while the main weight OF the rock dIags on
the stone floor Into this bed from 800 to 800 pounds
or more of sulphuets thrown, quicksilver added,
and stream of water turned on to It, A mule Is
hitched to the shaft on a floor above, and
he drags the head stones around over the
sulphurets until they are pulvenzed INTO
almost mpalpable powder, and then they are PANIED
out just as prospectQrs pan earth IN gulches, or
sluced off over amalgamated plates. Some stamp
1
suphurets worked on the principle of the arastra
and other mills have wTought-iron barrels about
three feet in diameter and five feet long IN when are
half dozen large metal balls The sulphurets
are put in the barrels, about 800 pounds TO each, ana
the barrels about twenty revolutions per minute
The constant shifting of the talngs and rolling OF
the balls rapidly reduce tho base metals and separate
! the gold, which amalgamates with the mercury
mixed with it i'll the barrels These different pro-
cesses are usually run about twentyfour hours on
charge and then they are sluiced off and PANIED
ont by the ordinary panning process In Colorado the
gold is mainly found so mixed with the base metals
as to defy reduction and amalganatiOn, hence the
signal failure of mining operations there thus far
but this season will, / believe, thoroughly master
their most refractory ores, and enable that rich fer
Titory 10 resume its former yield of millions annually
In Montana the have thus far been easily mas
tered. Another process for crushing the ores is the
Gillian mlll-consisting of heavy metal pans hye
feet in diameter, in which the heavy metal wheels
TevOlve, weighing from one 10 two tuns each a
current of water flows constantly into each pan, the
main body of the gold is amalgamated with the mer
cury in the pans and the fine quartz issues through
screens over amalgamated plates just as IN stamp
mills. This process Of erushngis, think, preferable
to the stampmilIs, will do more work with less
power and wear and tear of machinery. but 1t re-
duires more care and skill III it's use, and for that
reason IS not SO acceptable there are no oTneT pro
measure of confidence but there are iuuumerable
patents for separating the gold after the ore is
crushed. Silver ores are usually roasted before crush
ing, and gold ores, intermixed with silver, are also
improved IOf reduction by roasting Silver ores con-
tanning 40 per cent or more OF lead can he reduced
readily by smelling as the lead serves to lux the
ore; bnt if less than 40 per cent of lead is
/ found in it, it cannot be smelted in this
section so as to pay, Lead is worth from 30 to 20
cents per pound, and salt $40 per l0O pounds. lhe
ingredients are too costly as yet for the reduction of
any other than the Galena silver ores, excepting
by the ordinary crushing and amal9amating process
in use to produce free gold, In Colorado some OF
their refractory smelted and the gold silver
"copper" &c, all run out in bars together, ana are
then shipped to Swansea for separation but do not
know the measure of success that has attended the
he Consolidated GreQOQV COMPANY
orado Is working by this process but has as yet PAID
no dividends
After run has been made in quartz mill, usually
from one to three weeks, they clean up. The bat
teries or pans are run down low and then the
mercury and remaining fine quartz scooped out for
the process Of panning. small pan Is hlled with
the quartz and quicksilver out of the battery, and
whTled around in the water until the sand and earth
washed out and nothing but the mercury holding
the gold and heavy sulphurets remain. The quick
silver is then poured out from under the particles OF
ore and iron magnet is run through 1t TO separate
the particles OF pure IRON and the residue, which
contains gold in iron, is puverzed in hard mortar,
and what little gold be saved is gathered in mer
curry. The amalgamated plates over which the pull
verified has been passed then carefully scTaped
with square pieces of rubber, and the gold linked
with mercury is added 10 the mercury from the bat
teries. The taings caught in the boxes and rpples
are then emptied to be worked in arastra
barrels. The quicksilver gathered from the plates
and batteries then contains all the gold saved by
the iron, but the gold is in invisible particles in the
mercury. The mercury Is then strained ont OF the
gold through buckskin, leaving 30 many ounces of
amalgam" as the clean up The amalgam is worth
from s. TO 81 per ounce depending upon the me or
in its particles being the most valuable, the
curry can be better strained out Of it,
The amalgam is about the consistency OF thick
meal mush and nearly the same colOr-the gold Civ
ing the mercury soft yellow color II has yet TO be
retorted before it is pure gold. The amagam is
placed in little iron box, much like a brick-mold
full of fine needle holes The box is so constructed
as to allow the lid to be pressed down with clamps
and screws until the amalgam is compressed in the
smallest possible space 1t is then set inside of
other iron box three times its size. and lid fitted
it perfectly alr-tght by means of clay joints In
the top of the larger box there is hole probably an
inch In diameter to which is attached pipe that
comes down to the level of the bottom OF the box at