Planchas de Plata, Sonora

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In the high country of northern Sonora, between the old Rancho Arizona and the Planchas de Plata. 3cPlanchas.jpg
In the high country of northern Sonora, between the old Rancho Arizona and the Planchas de Plata.

Planchas de Plata (Spanish for slabs of silver), sometimes called Bolas de Plata (balls of silver) is a historic silver-mining district near Nogales, Sonora, Mexico, and a few miles south of the border with the US state of Arizona. Native silver was discovered here in 1736 by Antonio Siraumea, a Yaqui Indian, on the Rancho Arizona of Bernardo de Urrea. Historian Donald Garate believes Urrea's Arizona Ranch to be the likely source of the name of the present US state of Arizona, and he claimed the origin of the name of the ranch was the Basque phrase "aritz ona" (good oak). [1] Other historians have, however, debated this. For more detail on the etymology of the name Arizona, see Arizona.

Nogales, Sonora City in Sonora, Mexico

Heroica Nogales, more commonly known as Nogales, is a city and the county seat of the Municipality of Nogales. It is located on the northern border of the Mexican state of Sonora. The city is abutted on its north by the city of Nogales, Arizona, across the U.S.-Mexico border.

Mexico Country in the southern portion of North America

Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometres (770,000 sq mi), the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the tenth most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity that is also the capital city and its most populous city. Other metropolises in the state include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.

Arizona state of the United States of America

Arizona is a state in the southwestern region of the United States. It is also part of the Western and the Mountain states. It is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah, Colorado, and New Mexico; its other neighboring states are Nevada and California to the west and the Mexican states of Sonora and Baja California to the south and southwest.

Prospecters and miners rushed to the area of the great silver discovery of October, 1736. It was given the name San Antonio de Padua by Justicia Mayor Juan Bautista de Anza when he arrived on the scene in November and ordered that all the silver that had been taken from the site be impounded and brought to Urrea's Arizona Ranch, some fifteen miles down the canyon.

Because the large pieces of silver were found in a placer deposit (unusual for silver, and unique for such large masses) the Spanish colonial government maintained that the silver was an artificial treasure trove and so belonged to the crown. The miners maintained that it was a natural placer deposit that belonged to the discoverers under Spanish law. The court case dragged on for years, and in the meantime, Spanish soldiers ejected the miners. [2]

Treasure trove amount of money or coin, gold, silver, plate, or bullion found hidden

Treasure trove is an amount of money or coin, gold, silver, plate, or bullion found hidden underground or in places such as cellars or attics, where the treasure seems old enough for it to be presumed that the true owner is dead and the heirs undiscoverable. The legal definition of what constitutes treasure trove and its treatment under law vary considerably from country to country, and from era to era.

Because his escribano (scribe), Manuel José de Sosa, dated all the impounding documents at Arizona, people in faraway places like Guadalajara and Mexico City were soon referring to the silver as the "silver of Arizona." Arizona became a household word in early 18th century Mexico, associated with great and sudden wealth. [3]

Guadalajara City in Jalisco, Mexico

Guadalajara is the capital and largest city of the Mexican state of Jalisco, and the seat of the municipality of Guadalajara. The city is in the central region of Jalisco in the Western-Pacific area of Mexico. With a population of 1,460,148 inhabitants, it is Mexico's second most populous municipality. The Guadalajara metropolitan area has a reported population of 5,002,466 inhabitants, making it the second most populous metropolitan area in Mexico, behind Mexico City. The municipality is the second most densely populated in Mexico, the first being Ciudad Nezahualcóyotl in the State of Mexico. It is a strong business and economic center in the Bajío region.

Mexico City Capital in Mexico

Mexico City, or the City of Mexico, is the capital of Mexico and the most populous city in North America. Mexico City is one of the most important cultural and financial centres in the Americas. It is located in the Valley of Mexico, a large valley in the high plateaus in the center of Mexico, at an altitude of 2,240 meters (7,350 ft). The city has 16 boroughs.

Some modern writers on lost mines have assumed Planchas de Plata to be "lost," although the location has always been well known.

After the initial placer silver discovery, the district was idle until silver veins were discovered in the vicinity, and between 1872 and the 1930s, at least six mines operated, and ore was treated by a stamp mill and pan amalgamation. The amount of silver produced is not known, although the amount of ore mined has been estimated as between 50,000 and 100,000 tons. [4] No mining has been done since the 1930s, but a Canadian firm has had some encouraging results from exploration drilling in 2007. [5]

Stamp mill type of mill machine

A stamp mill is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation.

The Pan amalgamation process is a method to extract silver from ore, using salt and copper(II) sulfate in addition to mercury. The process was widely used from 1609 through the 19th century; it is no longer used.

References and further reading

  1. Donald Garate, 2005, "Arizonac, a twentieth-century myth", Journal of Arizona History 46(2), pp. 161-184
  2. Patricia Roche Herring, 1978, "The silver of Real de Arizonac," Arizona and the West , v.20, n.3, p.245-258.
  3. Arizona / Planchas de Plata
  4. Lawrence Segerstrom, 1986, Geologic setting and silver mineralization in the Planchas de Plata area, northern Sonora, Mexico, M.S. Thesis, Univ. of Arizona, Tucson, p.8-9
  5. Minefinders Corp. Planchas de Plata project /

This article incorporates text from Arizona / Planchas de Plata, a public domain article produced by the US National Park Service.

The public domain consists of all the creative works to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable.

National Park Service United States federal agency

The National Park Service (NPS) is an agency of the United States federal government that manages all national parks, many national monuments, and other conservation and historical properties with various title designations. It was created on August 25, 1916, by Congress through the National Park Service Organic Act and is an agency of the United States Department of the Interior. The NPS is charged with a dual role of preserving the ecological and historical integrity of the places entrusted to its management, while also making them available and accessible for public use and enjoyment.

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