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I58 . POLITICAL ESSAY ON THE [BOOK iv.

foliated gypsum.- At Sierra de Pinos near
Zacatecas, this metal is constantly accompanied
with blue radiated copper (straklige k"apferla-
zur) crystallized in small four sided prisms.

A great part of the silver annually produced
in Europe, is derived from the argentiferous
sulphuret of lead (silberizaltiger bleiglanz) which
is sometimes found in veins traversing pri-
mitive and transition mountains, and sometimes
in particular strata (ergfloze) in rocks of se-
condary finrmation. In the kingdom of New
Spain, the greatest part of the veins contain
likewise some argentiferous galena; but there
are very few mines in which the lead ore is a
particular object of their operations. Among
the latter, we can only include the mines of
the districts of Zimapan, Parral, and San
Nicholas de Croix. I observed that at Guanax-
uato, as well as several other mines in Mexico *,
and every where in Saxony, the varieties of
galena contain the more silver, the finer they
are in the grain.

* Among the varietes of galena, particularly rich insilver, and of very fine grain, may be specified those of the new mine of Talpan, in the Cerro de las Vegas, belonging to the district of Hostotipaquillo. This galena, which sometimes passes into compact antimonial sulphuret of lead (bleischweif is accompanied with much copper pyrites, and carbonate of lime.

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A very considerable quantity of silver is produced from the~smelting of iron pyrites (gemeiner schwefizl/vies) of which New Spain sometimes exhibits varieties richer than the glaserz itselfl It has been found in the Real del Monte, on the vein of Biscaina, near the pit of San" Pedro, the quintal of which contained even so much as three marcs of silver. At Sombrerete, the great abundance of pyrites disseminated in the red silver ore, is a great obstacle to the process of amalgamation.

We have described the ores which produce the Mexican silver, and it remains for us to examine into the mean riches of these minerals, considering them as all mixed together. It is a very common prejudice in Europe, that great masses -of native silver are extremely common in Mexico and Peru, and that in general the mineralised silver ores destined to amalgamation or smelting, contain more ounces, or more marcs of silver to the quintal, than the poor ores of Saxony and Hungary. Full of this prejudice, I was doubly surprised on my arrival in the Cordilleras to find that the number of poor mines greatly surpasses those of the mines to which in Europe we give the name of rich. A traveller who visits the famous mine of Valenciana in Mexico, -after having examined the

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and Schemnitz, can scarcely conceive how a vein which, for a great part of its extent contains the sulphuret of silver disseminated in the gangue in almost imperceptible particles, can regularly supply thirty thousand marcs per_ month, a quantity of silver equal to the half of what is annually furnished by all the mines of Saxony. It is no doubt true that blocks of native silver (papas de plata) of an enormous weight, havebeen extracted from the mines of Batopilas in Mexico and Guantahajo in Peru; but when we study attentively the history of the principal mines of Europe, we find that the veins of Kongsberg in Norway, Schneeberg in Saxony, and the famous metallic repository of Schlangenberg in Siberia, have produced masses of much more considerable bulk. We are not in general to judge from the size of the blocks, of the wealth of Ikthe mines of different countries. France does not altogether produce more than 8000 marcs of silver an!-' nually; and yet there are veins in that country (those of .Sainte-Marie-aux-Mines) from which amorphous masses of native silver have been extracted, of the weight of 30 kilogrammes. *

It appears that at the period of the formation of veins in every climate, the distribution of

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silver has been very unequal; sometimes con-
centrated in one point, and at other times dis-
seminated in the gangue, and allied with other
metals. Sometimes in the midst of the poor-
est ores we find very considerable‘ masses of
native silver; a phenomenon which appears
to depend on a particular operation of che-
mical aflinities, the mode of g action and laws
of which we are completely ignorant of.
The silver instead of being concealed in ga-
lena, or in pyrites in a small degree argen-
tiferous, or of being distributed throughout
all the mass of the vein over a greatextent,
is collected into a single mass. In that case
the riches of a point may be considered as
the principal cause of the poverty of the neigh-
bouring ores ; and hence we may conceive why
the richest parts of a vein are found separated
from oneanother by portions of. gangue almost
altogether destitute of metals. In Mexico, as
well as in Hungary, large masses of native silver
and glaserz, appear only in nests or kidneys,
(par rognons ;) and the compound rocks ex-
hibit the same phenomena as the masses of
veins. When we examine with care the struc-
ture of granites, syenites, and porphyries, we
discover the effects of a particular attraction in
the crystals of Mica, amphibole and feldspar,
of which a great number are accumulated in
voL. 111. M

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one point, while the neighbouring parts are
almost entirely destitute of them.

Although the New Continent, however, has
not hitherto exhibited native silver in such con-
siderable blopks as the Old, this metal is found
more abundantly in a state of perfect purity in
Peru and Mexico, than in any other quarter of
the globe. In laying down this opinion, I am
not considering the native silver which appears
in the form of lamellse, branches, or cylindrical
filaments in the mines of Guantahajo, Potosi,
and Gualgayoc, or in Batopilas, Zacatecas, and
Ramos. I found my opinion rather on the
enormous abundance of the ores called pacos
and colorados, in which silver is not mineralised,
but disseminated in such small particles, that
they can only be perceived by means of a micro-
scope. -

The result of the investigations made by Don‘ Fausto d’Elhuyar, the director general of the mines of Mexico, and by several members of the superior council of mines, is, that in uniting together all the silver minerals annually extracted, it would be found from the mixture, that their mean produce is from 0.0018 to 0.0025 of silver, that is to say in the common language of miners, that a quintal qfore (of one hundred pounds, or 16,000 ounces) contains

flom three to finer ounces of silver. This im

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