1910 Álamos Mining Overview

This is taken from the Mining and Scientific Press – April 16, 1910 – page 553.
Photos of Aduana, Sonora, Mexico in 1995 by Anders Tomlinson.

Álamos – Promonitos District by T. P. Brinegar.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

In the windy hills of Aduana mining ghosts are there to be seen and felt.

The mines which constitute this group are on the mineral zone which crosses the Alamos
Mountains about seven miles west of Alamos, Sonora, Mexico. The heart of the zone lies
within a rectangular surface 1.5 miles by 4 miles long, which commences at the Zambona
mine, near Minas Nuevas, on the northeast, and extends southwest to include the Old
Promontorio and San José mines. Precious metals were discovered in this region early
in the eighteenth century, and the quantities yielded by this group alone have exceeded
$100,000,000 in value. According to Camboa’s ‘Treatise on Mining” one remittance, in
1799 under charge to Alvarez, amounted to more than 1600 bars of silver. Humboldt noted
in his records, 1808, that he “passed a train of over one thousand mules loaded with
bars of silver from these mines on their way to the City of Mexico.” The production
became so great that the Government was induced to establish a mint in Alamos for the
special purpose of coining the metals produced at this point.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

Thousands of people have lived and mined here.

The geological formation is clearly revealed. The basel rock of the region is granite
which has been disturbed by powerful deep-seated forces. From these earth-disturbances
originated two well defined fissure-zones. The uplift of the earth-crust on the southwest
formed the Alamos mountains, and its subsidence on the northwest resulted in many
irregular folds, which were covered by extensive volcanic eruptives, chiefly of an
andesite type. In turn this was covered by sediments, the larger part being limestone.
The conditions were favorable for erosion, which reduced the elevation several
thousand feet. The fissure-zones, under present surface conditions, are about 5,000
feet apart, striking in a northeast direction. Both have granite ‘floors’ or foot-walls,
and dip toward each other. Between them is a ‘core’ of andesite porphyry which forms the
hanging wall of each vien-zone. This core was the was the centre of subsequent dynamaic
activity, shown by the evidence of upheavals and the rearranged condition of the strata.
In it are found many igneous dikes. Constant movement between the walls of the fissure-
zones served to keep them open to the free circulation of mineral-bearing solutions.
Cerra Cacharamba, a volcanic ‘neck’ 3700 feet above sea-level, is the landmark of the
district, and Humboldt during his visit to the camp in 1908, wrote figuratively that,
“Cacharamba rests on a bed of silver”. It seems that the past hundred years of mining
near its base has demonstrated that the great scientist was not far amiss in his rhetoric.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

To think here was once the world’s great silver mines .

The fissure-zones have been designated as east and west contacts. The east contact
is the ‘mother-lode’ of the zone, and is generally known as the Promontoric – Quintera
vein. The names of the productive mines situated on the several big ore-shoots of the
vein are, Old Promontories, Quintera, Santo Domingo, and Zambona. The Púlipito on
the north and the Nueva Promontorio on the south are new properties in course of
development and which have mineralized veins that promise future productiveness.
generally, mixed ores are extracted from mines on the east contact, which are found
in the form of oxides near the surface and turn into rich sulphides in depth. Some of
the ore-shoots are over 700 feet long, and in many places over 40 feet wide. Gray copper
is the principal ore from this lode, and its fabulous quantities and high silver content
are almost unparalleled in the annals of mining. These mines are owned by different
companies, each of which has more ‘likely’ ground that it will explore
in a score of years.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

How far away could the mining smoke be seen?

The west contact is best known as the san Jose – Claraboya vein. Through the
past two centuries it has remained comparatively unexplored. The mineral de
Santa Rosa ( Claraboya ) is said to be the oldest in the camp, and from the
large drill-holes found in the old Tajos ( open cuts ). one can give credence
to the tradition that ” it was the rich mine of the early fathers.” The San Jose
– Claraboya is a well defined vein of creamy to reddish – brown quartz, as shown
in the workings on the lower levels of the two mines of the same names. In the
upper workings or shear zone, the vein branches into seven parts, all of which
unite in depth forming a large body about 40 feet wide. The groups of mines which
have been under process of development during the past year are: Claraboya, San-Jose,
San Clemente, and Plata-Fina. El Ultimo, Parra, and Olividos are held as important
prospects. The ores from the mines on the west contact yield native silver, oxides,
and gold. They are very docile, and readily yield to simple economic treatment.
The assay values range from 15 to 5000 oz. silver and up to $70.00 in gold. The old
dumps of the Claraboya have been very profitable to the owner who has been reworking
them during the past two years. His developing the mine which an “adit which is
giving good results.
“(?) The San Jose is regarded as the ‘mascot’ of the camp.
It was bought by G.W. DuPes about a year ago, since which time he has been developing
and shipping ore, and erecting machinery. The Plata-Fina is between the San Jose and
Claraboya, and adjoining them. It is being developed by a shaft on the junction of
several veins. The San Clemente is owned by Rafael Ibara, president of the town of
Promontories. The ore extracted more than pays expenses, and the owner regards it
as the best prospect he has ever owned. These new workings, along with the Pulpito
and Nueva Pomomtorio on the east contact, go to show what great possibilities await
the judicious investment of capital along these two great fissure-veins. Side by
side with these great mines are many undeveloped prospects that, judge by surface
indications, warrant exploration.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

life goes on as past, present and future coincide.

The district possesses favorable economic conditions for mine operations. The
altitude averages about 2,000 feet above sea-level, and gives a climate, modified
by the gulf-breezes, that is as healthy as any place on the Pacific Ocean. Water
is abundant and of the best quality. The west part of the zone as access to the
wooded hills to the southwest where such fuel is cheap. The transportation facilities
are now good, as the recent completion of the Southern pacific Railroad of Mexico
affords an outlet from Mínas Nuevas, and good wagon – roads lead to Masiacs, also
on the railroad, and to the nearby seaport of Agiabampo. The cost of living
and freighting is low.

mine ruins in la aduana, sonora, mexico. which is seven miles west of alamos, sonora, mexico  photo by anders tomlinson

The Sonoran foothills are resting as La Aduana goes on and on.

 This was given to me by a man who had learned of my interest in Álamos, Sonora,
Mexico history. He asked me to visit his home that evening on Calle Madero. He told
me that he had once been the city manager of Álamos, Sonora, Mexico and took
pleasure in sharing his history library. He gave me the above article. I will
look in my Álamos notes for his name: He may have been Jose Fabian Villegas Puentes.

When T. P. Brinegar wrote this the Alamos mint had been closed for 15 years. Most of
the mines had closed by 1909 because of politics, revolution and expensive quicksilver
making mining unprofitable. The railroad from Alamos to Navajoa started operations
in 1907 and would stop in 1933. Mr. Brinegar seems to have been a mining industry
promoter, ever the optimist, and saw things more with his heart than his mind.
None-the-less, this article does give one a sense of the geology and scope of
Aduana – Promotories mining… Anders Tomlinson

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