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

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, and a few miles south of the border with the US state of

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

Native silver Silver is a chemical element; it has symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Silver is found in ...

was discovered here in 1736 by Antonio Siraumea, a

Yaqui The Yaqui, Hiaki, or Yoeme, are an Indigenous people of Mexico and Native Americans in the United States, Native American tribe, who speak the Yaqui language, a Uto-Aztecan language. Their primary homelands are in Río Yaqui valley in the no ...

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

, and he claimed the origin of the name of the ranch was the Basque phrase "aritz ona" (''good oak''). Other historians have, however, debated this. For more detail on the etymology of the name Arizona, see

. Prospectors 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 A 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 he ...

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. Because his ''escribano'' (scribe), Manuel José de Sosa, dated all the impounding documents at Arizona, people in faraway places like

Guadalajara Guadalajara ( ; ) is the capital and the most populous city in the western Mexican List of states of Mexico, state of Jalisco, as well as the most densely populated municipality in Jalisco. According to the 2020 census, the city has a population ...

and

Mexico City Mexico City is the capital city, capital and List of cities in Mexico, largest city of Mexico, as well as the List of North American cities by population, most populous city in North America. It is one of the most important cultural and finan ...

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. 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 A stamp mill (or stamp battery or stamping mill) is a type of Mill (grinding), mill machine that crushes material by pounding rather than Mill (grinding), grinding, either for further processing or for extraction of metallic ores. Breaking materia ...

and

pan amalgamation 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. The patio process had been used ...

. 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. No mining has been done since the 1930s, but a Canadian firm has had some encouraging results from exploration drilling in 2007.Minefinders Corp. Planchas de Plata project
/

References and further reading

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article produced by the US

National Park Service The National Park Service (NPS) is an List of federal agencies in the United States, agency of the Federal government of the United States, United States federal government, within the US Department of the Interior. The service manages all List ...

External links

Canadian company acquires historic Planchas de Plata district
at

. {{DEFAULTSORT:Planchas De Plata, Sonora Geography of Sonora Pre-statehood history of Arizona Silver mines in Mexico 1736 establishments in North America Silver mining in the Spanish Empire