The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1897-09-17
MODERN GOLD MINING.
Dates from the Return of Columbus
to Spain-Mexican Processes.
Modern Machinery

The modern history of gold and silver
mining begins with the return OF Colum.
bullion had fallen far below the require
ments of trade, and there were only $780,
0o0, 900 worth known to be available for ex-
change. The return of Queen Isabella
cases of jewels, bestowed on the navigator
for his venture, filled the Golfers and prose-
cuted the wars Of Spain for three centuries.
From four and a half millions of gold pro-
duced annually in the sixteenth century,
the figure has run up to near sixty mil
lions per annum in the nineteenth, but the
only important discovery in the process OF
extraction of gold in forty centuries prior
to 1S49 was the chemical affinity of mer-
curry for the precious metals. The use of
quicksilver is of great antiquity; the elder
Pliny referred to it as fact we'll known.
But posing as they did as fair gods, the
SpaniardS claimed to have invented the pro-
cess of amalgamation, which they intro
duced into the mines of Mexico after the
conquest. They first applied it to quartz
mining by a system of working invented
by Bartholomew Medina in 1857, one of the
first born of the invading Spanards. When
the CheapnesS of MeXican-Indian labor is
considered the extremely low grade of the
ores worked and the scarcity of fuel and
water power, the primitive simplicity of the
patio process, archaic as it seems could
scarcely be improved upon for the region,
and so thorough is the extraction of the
precious metals that mills will never be
erected to work up the tailings as is now
done in newer. rich regions where the early
working was wasteful. For $50 years, twen-
ty generations of men and women, as the
short generations go among these toilerS
of Mexico, have crushed rock by hand with
heavy hammers, and like slaves are still
at their tasks.
In the patio process the quartz. broken by
the hammers to the size of ones fist, is
sent to the stamping mill, most primitive
apparatus driven by mules. A long hori-
zontal shaft in the center is armed with
half a doZeu cams placed on an axle, so
as to act in succession on the projecting
teeth of the upright wooden stamps shOd
with iron, each weighing about two hum
dred pounds and working In correspond
ing mortar, in front of which is placed a
screen pierced with small round holes. With
human rock breakers and this crude bat
terry of eight Stampers three tons of ore
can be reduced to powder in day; a task
the first part of which the immense Gates
crusher accomplishes in one min
ute. The graduated ore is then
be still further reduced by the aid of water
to an impalpable slime. The grinding stones
and lining of the arastra are made of por-
phyry, smooth as glass and imperceptibly
joined. The araStra is about twelve feet in
diameter and is worked by mules which
turn a vertical shaft armed with crossbars
From the arastra the auri-argen tiferous
mud is removed to reservoirs and partly
dried by the sun. It is then transferred to
the patio or amalgamating floor a paved
space hundreds of feet square. where the
mud Is spread in fiat circles forty feet in
diameter and six inches in depth Salt and
mercury are added. and other chemicals,
according to the character of the ore. after
which the mules trample the mass every
day for two weeks in summer and often
ter. before the amalgamation is
complete. The waste matter is then
and the amalgam collected and retorted
This was practically the method of quartz
mining in the early days Of California until
mills were erected in the rich gold regions
of Nevada county. But until the opening of
the Comstock mines in the sixties placer
and hydraulic mining offered greater re-
wards for both individual and combined eff
forts. and as will be seen hereafter these
had their place in the development of the
machinery of mining.