Though known from remote times, the date of the first opening of the
famous mines of quicksilver of Almadén has not been precisely
determined. Almost all the writers on the subject agree that cinnabar,
from Spain, was already known in the times of Theophrastus, three
hundred years before the Christian era, although there is evidence in
the writings of Vitruvius that they were worked at a still earlier
date, Spanish ore being sent to Rome for the manufacture of vermilion.
Such ore constituted a part of the tribute which Spain paid to Rome
emperors, and there are records of its receipt until the first century
after Christ. The history of Almaden during the reign of the Moors is
so much involved in doubt that some writers deny altogether that the
Arabs worked the deposit; still the very name it now bears, which
means "the mine," and many of the technical terms still in use, give
evidence that they knew and worked that famous deposit. As for their
Christian conquerors, there are stray indications that they extracted
mercury during the twelfth and thirteen centuries. In 1417, Almaden
was given the privileges of a city, and from 1525 to 1645 the working
of mines was contracted for by the wealthy family of Fugger, of
Augsburg, Germany. Since then, the mine has been worked by the state,
though the Rothschilds have controlled the sale of the product.
According to Vitruvius, the works for manufacturing vermilion from
Spanish ore in Rome were situated between the temple of Flora and
Quirino. The ore was dried and treated in furnaces, to remove the
native mercury it contained, and was then ground in iron mortars and
washed. In addition, small quantities of quicksilver and vermilion
were made at Almaden. The ancients describe other methods, among which
Theophrastus speaks of using vinegar, which, however, appears from
modern investigations to have been an erroneous account. Nothing
definite is known concerning the methods of the Moors; we possess only
as a proof that they produced mercury, an account of a quicksilver
fountain in the marvelous palace of Abderrahman III., at
Medina-Zahara, and the works of Rasis, an Arab. The Moors probably
extracted mercury at Almaden, from the eighth to the twelfth century,
by the use of furnaces called "xabecas," which latter, in the
fourteenth century, were still employed by the Christians, who
continued them till the seventeenth century, when German workmen
replaced them by "reverberatory" furnaces, which in turn were
superseded in 1646 by aludel or Bustamente furnaces. There is an
anonymous description of the working with xabecas as practiced at
Almaden in 1543, and later accounts in 1557 and 1565. The ore was put
into egg-shaped vessels with a lid, the mineral being covered over
with ashes. The vessels were packed in a furnace heated with wood,
about 60 pounds being used per pound of quicksilver made. This system
was also applied at the Guancavelica mines, discovered in Peru in
1566, where the xabecas were abandoned in 1633, being replaced by the
furnaces invented by Lope Saavedra Barba, which there were called
"busconiles," while in Spain they were named Bustamente furnaces, and
elsewhere aludel furnaces. They were introduced at Almaden thirteen
years after their first use in Peru by Juan Alfonso de Bustamente,
Barba and his son having been lost at sea on their way to the
Peninsula. In 1876, there were at Almaden, at the works at Buitrones,
twenty such aludel furnaces and two Idria furnaces. D. Luis de la
Escosura y Morrogh, from whose work we take the above notes, has
followed the historical details of the growth of Almaden closely, and
from his account of the method of working in 1878 we take some data:
It is not an easy matter to explain the classification of the ore at
Almaden. _Metal_ is there called the richest mineral, composed of
quartz impregnated with crystalline cinnabar. _Requiebro_ are
middlings of medium richness, _China_ are smalls, and _Vaciscos_ the
finest ore. Besides native mercury, which the ores of Almaden contain
in greater or smaller quantity, the most abundant mineral is cinnabar,
which is always crystalline and is often crystallized. The ores have,
besides, a small quantity of selenium and iron pyrites intimately
mixed with the cinnabar. The gangue is quartz, occasionally
argillaceous and bituminous. The following are assays of some of the
ores made by Escosura:
Metal. Requiebro. Vaciscos. China.
1 2 3 4 5 6 7 8
Cinnabar 29.1 21.2 13.3 10.2 5.1 2.8 1.2 0.86
Iron pyrites. 2.2 2.0 2.0 1.9 12.3 1.5 2.1 2.80
Bituminous matter 0.6 1.0 1.0 1.2 4.6 0.7 3.4 0.90
Gangue 67.5 74.8 82.1 76.5 77.5 93.3 90.2 93.50
---- ---- ---- ---- ---- ---- ---- -----
Total 99.4 94.0 98.8 98.9 99.5 98.3 98.7 98.06
Quicksilver 25.05 18.28 11.47 8.64 4.40 2.41 1.03 0.75
It appears to be a difficult matter to determine the average
percentage of the various grades of ore. In 1872, a commission
classified and sampled a lot of 300 tons with the following results:
Quantity, Per cent. Average of
Grade. No. kilos. mercury. grade.
Metal { 1. 81,890 23.86 }
{ 2. 14,970 22.65 } 24.80
Requiebro { 3. 12,240 15.20 }
{ 4. 17,000 10.50 } 12.47
China { 5. 31,890 3.84 }
{ 6. 32,360 1.17 } 1.75
{ 7. 28,960 0.10 }