quicksilver for one of gold; and about two-thirds of the gold is caught
thus. The copper plate in quartz-mills is made in the same manner as in
placer-sluices, under which head a description of the plate may be
found. Some amalgamating bowls or basins are little Chilean mills and
arastras, made of cast iron. One plan of amalgamation is to use a cast
iron bowl about four feet in diameter and a foot deep. Near the bottom
are horizontal iron arms, which revolve and stir the quicksilver and
pulverized quartz together. Four or five of these bowls sit in a row
but at different levels: the bottom of the first bowl being level with
the top of the second, and so on. The pulverized quartz passes through
them all. Under each bowl a fire is kept up, because heat forms the
action of amalgamation. If there be any pyrites in the quartz, some
common salt is thrown in to assist in releasing the gold from the
embraces of the sulphurates, and preparing it to be seized by the
mercury. Another amalgamating bowl revolves on an axis that stands at
an angle of about seventy-five degrees to the horizon, so that the
material in the bowl is continually moving; and the bottom is divided
by little compartments, which make a constant riffle. In other bowls
the pulverized quartz is forced with water through the mercury. The
methods of amalgamation differ very much, and a book might be filled
with a description and discussion of the processes used at different
quartz-mills in California.
_Sulphurets._--Many auriferous quartz veins contain considerable
quantities of sulphurets or pyrites of iron, copper and lead, and their
presence prevents amalgamation, and thus causes a great loss of gold.
It is said that on some occasions in good mills, not more than twenty
or thirty dollars have been obtained from a ton of vein-stone which had
seven or eight hundred dollars of gold in every ton. The best method of
treating the quartz containing pyrites, is to roast it, and thus drive
off the sulphur, but this process is so expensive that it is seldom
used; and the common practice is to crush and amalgamate the rock, and
save the concentrated tailings for some future time, when there may be
a sale for them, or when it will be cheaper to reduce them. The
pulverized sulphurets are decomposed by exposure to the air, and after
the tailings have been preserved for a time, they may pay better at the
second amalgamation than at the first. A mixture of common salt assists
the decomposition of the pyrites.
_Chief Quartz-Mills._--The most productive quartz-mill in the state is
the Benton mill, on Fremont's Ranch, in Mariposa county. It is also the
largest, having forty-eight stamps. There are four mills on the estate,
with ninety-one stamps in all, and their average yield per month is
sixty thousand dollars. A railroad four miles long, conveys the quartz
from the lode to the mills. The Allison quartz mine in Nevada county,
produces forty thousand dollars per month. The Sierra Buttes
quartz-mill, twelve miles from Downieville, yields about fifteen
thousand dollars per month. These last mills run night and day, and
crush and amalgamate ten thousand tons of rock a year, or twenty-eight
tons per day. Forty men are employed, twenty-five to quarry the rock,
five in the mill to attend to the stamps and amalgamation, one to do
carpentry, one for blacksmithing, and eight for getting out timber,
transporting quartz, and so forth. The cost of quarrying, crushing and
amalgamating a ton of rock, is six dollars. The wages of the men are
from fifty to seventy dollars per month with boarding. The average
wages is sixty dollars. About ten miles eastward of Sonora, in Tuolumne
county, are some rich veins of auriferous quartz, the most prominent of
which are the Soulsby and Blakeslee lodes. The Soulsby mill produced
forty thousand dollars in three weeks, when it commenced work in 1858,
but it has not been so profitable of late.
_Silver Mining._--Silver mining has not yet been established fairly as
a business in California. The silver ores of Washoe were discovered in
1859, and mining has been fairly commenced there, but the mines of
Esmeralda and Coso, within the limits of this state, were not found
until the summer of 1860, and up to the present time no mills have been
established there.
Silver mining differs much from gold mining. Gold is always found as a
metal, never as an ore, and the separation from the accompanying
vein-stone with which it is mixed mechanically, is much more simple and
easy than the reduction of the argentiferous ores in which the silver
is chemically combined with base substances, for which it has a strong
affinity. Chemical knowledge and chemical processes are more necessary
in mining for silver than for gold; and while all auriferous quartz is
of the same kind, and may be treated in the same manner, there are many
different kinds of silver ores, each of which requires a peculiar
treatment. The reduction of silver ore costs on an average, from three
to five times as much as the reduction of auriferous quartz.
The silver ore of Esmeralda and Coso is a sulphuret of silver, nearly
all the veins having the same material, though the amount of it
scattered through the vein-stone differs greatly in different lodes. In
some veins there is much free gold, that is, little specks of metallic
gold which can be separated from the other material in the same manner
that gold is separated from auriferous quartz. The methods of reducing
silver ore are so numerous and complex, and vary so much in different
districts and under different circumstances, that it is impossible to
know now what process will be used in Esmeralda and Coso, the resources
of which places have been so little studied. Besides it is said that
new processes for reducing silver ore have been invented, far superior
to all the old methods; and these processes are kept secret. It is
therefore unnecessary that I should go into a long description of the
various processes practised elsewhere. Silver ore after pulverization
is smelted by mixing with it fifty per cent. of lead in metal or ore,
and ten per cent. of iron, and exposing the whole to a heat sufficient
to melt the silver which runs off. The metal thus obtained is not pure
but contains much lead, which is driven off by heat while the silver is
kept in a molten condition for a period of four or six hours. The cost
of smelting in California at present, is about one hundred and
twenty-five dollars per ton. In most of the other methods of reducing
silver ore, the ore is roasted to drive off the sulphur. In the barrel
amalgamation, which has been used at Washoe, and will probably be used
at Esmeralda also, half a ton of ore, after being pulverized and
roasted, three hundred pounds of water, and one hundred pounds of
wrought iron, in little fragments, are put into a barrel, which
revolves on a perpendicular axis. At the end of two hours the mass has
taken the consistence of thick cream, when five hundred pounds of
quicksilver are put in, and after the barrel has revolved four hours
more, the amalgamation is complete. More water is now poured in; the
barrel revolves very slowly to let the amalgam all settle to the
bottom, the mud runs off through a cock four inches above the bottom,
and the mercury and amalgam are then drawn off through a little hole in
the bottom of the barrel.
_Quicksilver Mining._--The ore from which quicksilver is obtained is a
sulphuret. The sulphur is driven off by heat, and the metal, which
rises in fumes from the ore, is collected by condensation. The miners
are Cornishmen and Mexicans. The ore is in large masses underground,
not in a connected vein of regular thickness; and after one mass is
exhausted, much labor is often vainly spent in search of another. There
are, however, usually little seams of ore running from one large
deposit to another, and it is the business of the mining captains to
observe these veins closely, and trace them up when a "fault" occurs.
There are no scientific rules for finding the ore; and the business of
searching for the large deposits is never intrusted to educated mining
engineers, but always to mining captains, who have themselves been
laborers, and have learned by experience where to seek. The New Almaden
mine produces two hundred and twenty thousand pounds of metal in a
month. The _hacienda_, or reducing establishment of the mining company,
has fourteen brick furnaces, each fifty feet long, twelve feet high,
and twelve feet wide. At one end of each furnace is the fire chamber,
which may be nine cubic feet inside; next to that is the ore chamber of
about the same size; and beyond that is the condensing chamber, in
which there are a number of partitions alternately running up from the
bottom and down from the top, with a space for the fumes to pass, their
course being up and down, and up and down again, and so on, for a
distance of thirty feet to the chimney, which is forty feet high. In
the bottom of the condensing chamber is water. The walls between the
fire chamber and the ore chamber, and between the latter and the
condensing chamber, are built with open spaces, so that the heat, smoke
and fumes can pass through. The ore is placed in the ore chamber in
such a manner as to leave many open spaces. The heat drives off the
sulphur and mercury of the ore in fumes, which in passing through the
condensing chambers, deposit the mercury, and the smoke and sulphur
escape through the chimney. In the Enriqueta and Guadalupe mines the
quicksilver is condensed in a close iron retort, and the sulphur is
absorbed by quicklime.
Copper ore is dug from several mines in California, but it is all
exported to be smelted elsewhere.
_Platinum._--Platinum, iridium and osmium, three white metals of about
the same specific gravity with gold, are found with the latter metal in
the placers in the basin of the Klamath and Trinity Rivers. Their
particles are usually fine scales, very rarely reaching a quarter of an
ounce in weight, and the largest piece of either ever found was less
than an ounce and a half. They cannot be separated from the gold by
washing, but they do not unite with quicksilver, and therefore they are
separated from the more precious metal by amalgamation. They have no
regular market in the state; miners never make them the chief object of
search, and they have not been studied, so it is not known to what
extent they might be obtained.
_Del Norte and Klamath._--Del Norte county in the north-western corner
of the state, is about forty miles long from east to west by thirty
from north to south. The mining population in it is small. Most of the
mining is done along the banks of the Klamath River, which runs about
twenty miles through the south-eastern portion of the county. There are
some miners on the head-waters of Althouse Creek, which runs northward
into Oregon. The county assessor, in his report for 1860, does not
mention the existence of any quartz-mill or mining-ditch in the county.
The mining districts are very mountainous and difficult of access. They
obtain most of their supplies from Crescent City. The mining is chiefly
in shallow placers, in deep and narrow ravines, and on bars of the
Klamath River.
Klamath county lies immediately south of Del Norte, and is about the
same size. It is almost exclusively a mining county, and has a
population of about eighteen hundred. The diggings are placers in the
bars and banks of the Klamath River and its tributaries, the Trinity
and Salmon Rivers, and many small creeks. The principal mining places
are Orleans Bar, Gullion's Bar, Negro Flat, Cecilville, Weitspeck and
Red Cap. The whole county is very rugged and mountainous, and much of
it is covered with heavy timber. The diggings are so difficult of
access, and are so protected by mountains against ditches, that they
will last for many years. There is probably no part of the state where
the single miner, without capital, has a better chance to dig gold with
a profit. Nearly the whole beach of the county is auriferous.
_Siskiyou._--Siskiyou county lies east of Del Norte and Klamath, is
forty miles wide from north to south, one hundred miles long from east
to west, and reaches to the eastern boundary of the state. It has a
population of 7,629, the large majority of whom are engaged in mining.
The mining district is all in the western end of the county, along the
banks of the Klamath River and its tributaries, the Scott and Shasta
Rivers. The Klamath runs through a deep _canon_; the Scott and Shasta
Rivers, have pleasant open valleys, but the diggings along their banks
are chiefly among the _canons_ near the Klamath. Hydraulic and tunnel
claims are rare. There are six quartz-mills in the county, and fifteen
mining ditches, of which last the principal is the Yreka canal, forty
miles long, bringing water from the head of Shasta River to the town of
Yreka. In 1859, there were four quartz-mills in the county, one of
which was at Mugginsville, one in Scott's valley and two in Quartz
valley. I have no information about the situation of the two built
since that time. The principal mining towns are Yreka, Scott's Bar,
Hawkinsville, Johnson's Bar, Deadwood and Cottonwood.
_Trinity and Shasta._--South of the western part of Siskiyou and the
eastern part of Klamath, lies Trinity county, ninety miles long from
north to south, and about twenty miles wide on an average. The northern
part of the county is the basin of the Trinity River, and is
auriferous. From the county assessor's report for 1860, it is to be
inferred that there is not a quartz-mill or a mining-ditch in the
state. The county is very mountainous, and most of the mining is done
in rugged _canons_ along the Trinity River. The chief mining towns are
Weaverville, Cox's Bar, Big Bar, Arkansas Flat, Mooney's Flat and
Trinity Centre.
South of Siskiyou and east of Trinity lies Shasta county, which is on
an average forty miles wide from north to south and one hundred miles
long, reaching to the eastern border of the state. There is a rich
auriferous district about twenty miles square, in the vicinity of the
town of Shasta, in the south-western part of the county. The diggings
are mostly in the basins of Clear Creek, Cottonwood Creek, Rock Creek
and Salt Creek, all of which enter into the Sacramento. There are four
quartz-mills in the county, one at French Gulch, one at Middle Creek,
one at Muletown, and one at Old Diggings. The county has twenty-seven
mining ditches, with a joint length of one hundred and forty-one miles,
an average of five miles each. The chief mining towns are Shasta,
Horsetown, French Gulch, Muletown, Briggsville, Whiskey and Middletown.
_Plumas and Sierra._--South of the eastern part of Shasta county lies
Plumas, which is about seventy miles square. About one third of the
county, in the south-western part of it, comprising that portion
drained by the head waters of Feather River, is auriferous. It lies
high above the level of the sea, and the work of mining is interrupted
during a considerable portion of the winter, by cold, snow and ice.
Hydraulic and tunnel claims in deep hills, furnish a large portion of
the gold yield of the county. There are five quartz-mills, one at
Elizabethtown, one at Eureka Lake, and three at Jamison Creek. The
principal mining towns are Quincy, Jamison City, Indian Bar, Nelson's
Point and Poorman's Creek.
South of Plumas is Sierra county, which is fifty miles long from east
to west, and twenty miles wide from north to south. The North Fork of
the Yuba River runs through its centre, and the Middle Fork is its
southern boundary. Though small, it is one of the richest mining
counties of the state, and in proportion to the extent of its mining
ground, is much richer than any other county. All its territory is four
thousand feet above the sea level, at the lowest. Most of the mining is
done in hydraulic and tunnel claims in deep hills. Near the centre of
the county is a mountain called the Downieville Butte, or the Yuba
Butte, eight thousand eight hundred and forty-six feet high, on the
sides of which are found some rich quartz leads. In 1859 there were
eleven quartz-mills in Sierra county, of which seven are at the Butte,
two at Downieville, one at the Mountain House, and one at Sierra City.
The principal mining towns are Downieville, Monte Cristo, Pine Grove,
St. Louis, La Porte, Poker Flat, Eureka City, Forest City, Alleghany
Town, and Cox's Bar. One of the most remarkable features of the placers
of the state, is the blue lead, which was first discovered in Sierra
county, and has been more thoroughly examined there than elsewhere. The
"blue lead" is a stratum of blue clay very rich in gold. It is found
deep under other strata. The general opinion is, that the blue lead
occupies the bed of a large antediluvian river, which ran parallel with
the Sacramento and about sixty miles eastward of it. It has been traced
twenty miles or more, passing near Monte Cristo, Alleghany Town, Forest
City, Chip's Flat and Zion Hill. Mr. C. S. Capp wrote thus to the San
Francisco _Bulletin_:
"This is not one of the many petty leads, an inch or two in breadth and
thickness, which, after being traced a few hundred feet, end as
suddenly and mysteriously as they commence; but it is evidently the bed
of some ancient river. It is often hundreds of feet in width, and
extends for miles and miles, a thousand feet below the summits of high
mountains, and entirely through them. Now it crops out where the deep
channels of some of the rivers and ravines of the present day have cut
it asunder; and then, hidden beneath the rocks and strata above it, it
only emerges again miles and miles away. Wherever its continuity has
been destroyed, the river or gulch which has washed a portion of it
away, was found to be immensely rich for some distance below, and the
materials of which the lead is composed are found with the gold in the
bed of the stream. It is evidently the bed of some ancient stream,
because it is walled in by steep banks of hard bed-rock, precisely like
the banks of rivers and ravines in which water now runs, and because it
is composed of clay which is evidently a sedimentary deposit, and of
pebbles of black and white quartz, which could only be rounded and
polished as they are by the long continued action of swiftly running
water. The bed-rock in the bottom of this lead is worn into long smooth
channels, and also has its roughness and crevices like other river
beds. The lighter and poorer qualities of gold are found nearest to its
edges, while the heavier and finer portions have found their way to the
deeper places near the centre. Trees and pieces of wood, more or less
petrified and changed in their nature, which once floated in its
waters, are also every where encountered throughout this stratum.
"The clay and fine gravel in which these pebbles and boulders are found
to be tightly packed, is of a light-blue color, which gives the name to
the lead. Much of this clay is remarkably fine and free from coarse
particles, and is smooth and unctuous to the touch. It is said to be
strongly impregnated with arsenic, as was shown by chemical analysis,
and contains large quantities of iron and sulphur in solution, for
pyrites and sulphurets of iron are deposited in shining metallic
crystals in every vacant crevice. Fine gold is found among this clay,
and the heavier particles beneath it, upon the bed-rock. This stratum
varies in thickness from eighteen inches to eight or ten feet, while
the whole lead varies in width from a hundred and fifty to five hundred
feet.
"The same lead has been found at Sebastopol, four miles above Monte
Christo, and also higher up among the mountains. It appears at Monte
Christo, which is four miles above the high-lying Downieville, and over
three thousand feet above it, and at Chapparal Hill on the side of a
deep ravine; then at the City of Six, which is also on very high land,
about four miles from Downieville, across the North Yuba. It is next
found at Forest City, on both sides of a creek, and is there traced
directly through the mountain to Alleghany Town and Smith's Flat, on
the opposite side. There it is again cut in twain by a deep ravine. It
crops out on the other side at Chip's Flat, where it has been followed
by tunnels passing completely through the mountain to Centreville and
Minnesota on the other side. Here it is obliterated by the Middle Fork
of the Yuba, but it is believed to be again found at Snow Point, on the
opposite side of the river, and again at Zion Hill, several miles
beyond. There is no reason for doubting that after thus reaching over
twenty miles, it still extends further. Hundreds of tunnels have been
run in search of it. Where the line it follows was adhered to, they
have always found it, and have been well rewarded for their labor.
Millions of dollars have been taken from this lead, and its richness,
even in portions longest worked, is yet undiminished. These tunnels
have cost from $20,000 to $100,000 each, and interest in the claims
they enter sell readily at from $1,000 to $20,000, in proportion to the
amount of ground within them remaining untouched, and the facilities
which exist for working it. Many of these claims will yet afford from
five to ten or more years' profitable labor to their owners, before the
lead itself within them is exhausted. As in some of them quartz veins
and poorer paying gravel have been found, many of them may be valuable
to work from the top down as hydraulic claims."
This idea that the blue lead occupies the bed of an antediluvian river
is however not universally accepted. Mr. B. P. Avery, who has written
numerous newspaper articles upon the mineral deposits, asserts that the
"blue lead," as it is called, is not a "lead" but an extensive stratum
which is many miles wide, and is found all the way from the foot hills
to the summit of the Sierra Nevada. In reply to this, it is said that
while a bluish stratum of clay similar to that of the blue lead is
found over a wide district, that it is evidently different in origin
from the blue lead itself, which is confined to a narrow bed, and
marked by the signs found in all the other ancient river beds of the
state.
The Sierra Butte Quartz Mining Company has some of the best auriferous
quartz lodes in the state. One lode called the Cliff Ledge, is
twenty-five feet wide; and another called the Aerial Ledge, is about
three feet wide. In the Cliff Ledge, the paying rock averages about six
feet in thickness next the foot wall. The average yield is eighteen
dollars per ton. The quartz is bluish white in color, and very hard
when first taken from the lode, but on exposure to the air it slowly
crumbles into sand.
_Yuba and Butte._--West of Sierra county, and drained by the same
streams, is Yuba, which reaches to the Sacramento River, lying half in
the mountains and half in the plains, the mining district being in the
former half. The principal mining towns are Camptonville, Timbuctoo,
Foster's Bar, Texas Bar and Long's Bar. In 1859 there were nine
quartz-mills in the county, three at Brown's valley, and one each at
Camptonville, Dobbin's Ranch, Dry Creek, Honcut, Indiana Creek and
Robbin's Creek. The assessor in 1860 reported only two quartz-mills in
the county. There are twenty-two ditches in the county, with an
aggregate length of nine hundred and fifty-two miles, an average of
forty-three miles each. The most important ditch, called "Bovyer's,"
supplies Timbuctoo with five thousand inches of water in the winter,
less in the summer. The diggings at Timbuctoo are in a deep hill, which
is washed away by the hydraulic process.
West of Yuba and Plumas counties lies Butte, which is drained by the
Feather River. The principal mining towns are Oroville, Bidwell's Bar,
Forbestown, Natchez and Whiterock. In 1859 there were seventeen
quartz-mills in the county, of which four were at Oregon Gulch, at
Columbiaville and Hansonville, three each, two at Yankee Hill, and at
Evansville, Gold Run, Long Bar, Nesbitt's Flat and Spring Valley, one
each. The assessor reports for 1860, twenty-nine quartz-mills, worth
fifty thousand dollars, and crushing in the aggregate one hundred and
sixty-two and a half tons per day. There are sixty-four mining-ditches,
with an aggregate length of five hundred and eighty-three miles. The
bars and beds of Feather River were once very rich, and some of the
most extensive enterprises of river mining in the state have been
undertaken within the limits of Butte county. The greatest flume ever
built in California was that of the Cape Claim Company, near Oroville,
in 1857. It was three quarters of a mile long and twenty feet wide, and
furnished employment for two hundred and fifty men from May till
November. The expenditures during that period were $176,985, and the
receipts $251,426, showing a clear profit of $74,441. The next year,
after the water had fallen, the company commenced its labors again;
spent $160,000 and received $115,000, and thus lost $45,000. North of
Oroville is a "table-mountain" with a top of basalt, covering a rich
deposit of auriferous clay.