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Silver mining is the
extraction Extraction may refer to: Science and technology Biology and medicine * Comedo extraction, a method of acne treatment * Dental extraction, the surgical removal of a tooth from the mouth Computing and information science * Data extraction, the pr ...
of
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
from minerals, starting with
mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...
. Because silver is often found in intimate combination with other metals, its extraction requires elaborate technologies. In 2008, ca.25,900 metric tons were consumed worldwide, most of which came from mining.


Silver sources

Silver-bearing ore typically contains very little silver, with much higher percentages of copper and lead. Specific minerals include
argentite In mineralogy, argentite (from the Latin ''argentum'', silver) is cubic silver sulfide (Ag2S), which can only exist at temperatures above 173 °C, 177 °C or 179 °C. When it cools to ordinary temperatures it turns into its monocli ...
(Ag2 S),
chlorargyrite Chlorargyrite is the mineral form of silver chloride (AgCl). Chlorargyrite occurs as a secondary mineral phase in the oxidation of silver mineral deposits. It crystallizes in the isometric - hexoctahedral crystal class. Typically massive to colum ...
("horn silver," Ag Cl), polybasite (Ag, Cu)16Sb2S11), and proustite (Ag3AsS3). Silver mainly occurs as a contaminant in
chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mo ...
and
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cr ...
, important ores of
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
and
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
, respectively.Kassianidou, V. 2003. Early Extraction of Silver from Complex Polymetallic Ores, in Craddock, P.T. and Lang, J (eds) Mining and Metal production through the Ages. London, British Museum Press: 198–206 Some ores are actually mined explicitly for their silver value vs the silver being a byproduct of other metals. However silver is only found rarely in a
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...
form as nuggets, in placer deposits, and veins.Reddy, Rohan, 2019. Silver, Explained. Global X. https://www.globalxetfs.com/silver-explained/


Excavation

Methods for mining silver depend on the grade of the ore, its depth, host rock, and other economic factors. Commonly, silver ore is obtained from open pit mines, and underground drifts and shafts.Hilliard, Henry E., 2003. "Silver". USGS. Explosives are frequently used to shatter veins into manageable pieces, which are transported via mine cars and then lifted to the surface. The process can be dangerous.


Ore processing

Once removed from the mine, silver-containing ore is crushed (
commutation Commute, commutation or commutative may refer to: * Commuting, the process of travelling between a place of residence and a place of work Mathematics * Commutative property, a property of a mathematical operation whose result is insensitive to th ...
) into a fine powder to expose individual grains to chemical processing. As a byproduct of mining of lead and copper, silver ores are often purified by
froth flotation Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry, wher ...
. After froth flotation, silver is extracted by a cyanide process, akin to technology used for gold extraction. In some cases, the ore is treated by
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a c ...
before cyanide treatment. Silver is also produced during the electrolytic refining of copper and by application of the Parkes process on lead ores. Commercial grade fine silver is at least 99.9 percent pure silver, and purities greater than 99.999 percent are available.


Recycling

About 5000 tons of silver are annually recovered from scrap. Jewelry, photographic film, silverware, coins, electronics are sources of recyclable silver.


Production areas

The principal sources of silver are
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
, copper-
nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow t ...
,
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
,
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
, and
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
-
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
ores obtained from
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
,
Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
,
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
,
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...
,
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
and the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
.
Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
was the world's largest silver producer in 2014, producing 5,000
metric ton The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton (United States ...
s (161 million
troy ounce Troy weight is a system of units of mass that originated in 15th-century England, and is primarily used in the precious metals industry. The troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and th ...
s), 18.7 percent of the 26,800 tonne (862 million troy ounce) production of the world.


History

Silver mining has been undertaken since as early as the 5th century BCE. As silver is a
precious metal Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lu ...
often used for
coins A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order t ...
and bullion, its mining has historically often been lucrative. As with other precious metals such as
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
or
platinum Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Pla ...
, newly discovered deposits of silver ore have sparked
silver rush A silver rush is the silver-mining equivalent of a gold rush, where the discovery of silver-bearing ore sparks a mass migration of individuals seeking wealth in the new mining region. Notable silver rushes have taken place in Mexico, Chile, the ...
es of miners seeking their fortunes. In recent centuries, large deposits were discovered and mined in the Americas, influencing the growth and development of Mexico, Andean countries such as Bolivia, Chile, Argentina and Peru, as well as Canada and the United States. Silver has been known since ancient times. Silver is mentioned in the
Book of Genesis The Book of Genesis (from Greek ; Hebrew: בְּרֵאשִׁית ''Bəreʾšīt'', "In hebeginning") is the first book of the Hebrew Bible and the Christian Old Testament. Its Hebrew name is the same as its first word, ( "In the beginning" ...
, and slag heaps found in
Asia Minor Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
and on the islands of the
Aegean Sea The Aegean Sea ; tr, Ege Denizi ( Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans ...
indicate that silver was being separated from
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
as early as the
4th millennium BC The 4th millennium BC spanned the years 4000 BC to 3001 BC. Some of the major changes in human culture during this time included the beginning of the Bronze Age and the invention of writing, which played a major role in starting recorded history. ...
. The silver mines at
Laurium Laurium or Lavrio ( ell, Λαύριο; grc, Λαύρειον (later ); before early 11th century BC: Θορικός '' Thorikos''; from Middle Ages until 1908: Εργαστήρια ''Ergastiria'') is a town in southeastern part of Attica, Gree ...
were very rich and helped provide a currency for the economy of
ancient Athens Athens is one of the oldest named cities in the world, having been continuously inhabited for perhaps 5,000 years. Situated in southern Europe, Athens became the leading city of Ancient Greece in the first millennium BC, and its cultural achieve ...
, where the process involved mining the ore in underground galleries, washing and then
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a c ...
it to produce the metal. Elaborate washing tables still exist at the site which used rain water held in cisterns and collected during the winter months. The Romans took over silver mining in Spain from
Carthage Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classi ...
after their acquisition of Carthaginian territories there following the
Second Punic War The Second Punic War (218 to 201 BC) was the second of three wars fought between Carthage and Rome, the two main powers of the western Mediterranean in the 3rd century BC. For 17 years the two states struggled for supremacy, primarily in Ital ...
. Extraction of silver from lead ore was widespread in
Roman Britain Roman Britain was the period in classical antiquity when large parts of the island of Great Britain were under occupation by the Roman Empire. The occupation lasted from AD 43 to AD 410. During that time, the territory conquered wa ...
very soon after the Roman conquest of the first century AD. One of the main aims of the
Viking Vikings ; non, víkingr is the modern name given to seafaring people originally from Scandinavia (present-day Denmark, Norway and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded and se ...
expansion throughout Europe was to acquire and trade silver.
Bergen Bergen (), historically Bjørgvin, is a city and municipalities of Norway, municipality in Vestland county on the Western Norway, west coast of Norway. , its population is roughly 285,900. Bergen is the list of towns and cities in Norway, secon ...
and
Dublin Dublin (; , or ) is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 ...
are still important centres of silver making. An example of a collection of Viking-age silver for trading purposes is the
Galloway Hoard The Galloway Hoard, currently held in the National Museum of Scotland, is a hoard of more than 100 gold, silver, glass, crystal, stone, and earthen objects from the Viking Age discovered in the historical county of Kirkcudbrightshire in Dumfries ...
. From the mid-15th century silver began to be extracted from copper ores in massive quantities using the liquation process creating a boost to the mining and
metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...
industries of
Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...
.


Americas

Vast amounts of silver were brought into the possession of the crowns of Europe after the
conquest Conquest is the act of military subjugation of an enemy by force of arms. Military history provides many examples of conquest: the Roman conquest of Britain, the Mauryan conquest of Afghanistan and of vast areas of the Indian subcontinent, ...
of the
Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North America, North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. ...
from the now Mexican state of
Zacatecas , image_map = Zacatecas in Mexico (location map scheme).svg , map_caption = State of Zacatecas within Mexico , coordinates = , coor_pinpoint = , coordinates_footnotes = , subdivision_type ...
(discovered in 1546) and
Potosí Potosí, known as Villa Imperial de Potosí in the colonial period, is the capital city and a municipality of the Department of Potosí in Bolivia. It is one of the highest cities in the world at a nominal . For centuries, it was the location o ...
(Bolivia, also discovered in 1546), which triggered the
Spanish Price Revolution The Price Revolution, sometimes known as the Spanish Price Revolution, was a series of economic events that occurred between the second half of the 15th century and the first half of the 17th century, and most specifically linked to the high rate o ...
in Europe. Silver mining required large amounts of mercury to extract the metal from ore. In the Andes, the source was the Huancavelica mercury mine; Mexico was dependent on mercury from the
Almadén Almadén () is a town and municipality in the Spanish province of Ciudad Real, within the autonomous community of Castile-La Mancha. The town is located at 4° 49' W and 38° 46' N and is 589 meters above sea level. Almadén is approximately 3 ...
mercury mine in Spain. Mercury had a high adverse environmental impact. Silver was extremely valuable in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
, and became a global commodity.
Manila galleon fil, Galyon ng Maynila , english_name = Manila Galleon , duration = From 1565 to 1815 (250 years) , venue = Between Manila and Acapulco , location = New Spain ( Spanish Empir ...
s carried
Spanish dollar The Spanish dollar, also known as the piece of eight ( es, Real de a ocho, , , or ), is a silver coin of approximately diameter worth eight Spanish reales. It was minted in the Spanish Empire following a monetary reform in 1497 with content ...
s across the Pacific, contributing to the rise of the
Spanish Empire The Spanish Empire ( es, link=no, Imperio español), also known as the Hispanic Monarchy ( es, link=no, Monarquía Hispánica) or the Catholic Monarchy ( es, link=no, Monarquía Católica) was a colonial empire governed by Spain and its prede ...
. The rise and fall of its value affected the world market.In the first half of the 19th century Chilean mining revived due to a silver rush in the Norte Chico region, leading to an increased presence of Chileans in the Atacama desert and a shift away from an
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
based economy. The country of
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...
was named after its silver resources by Spanish conquistadors; Argentina is a Spanish adjective meaning "silvery". Silver mining was a driving force in the settlement of western
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, with major booms for silver and associated minerals (lead, mostly) in the
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cr ...
ore silver is most commonly found in. Notable
silver rush A silver rush is the silver-mining equivalent of a gold rush, where the discovery of silver-bearing ore sparks a mass migration of individuals seeking wealth in the new mining region. Notable silver rushes have taken place in Mexico, Chile, the ...
es were in
Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...
;
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
;
Cobalt, Ontario Cobalt is a town in Timiskaming District, Ontario, Canada. It had a population of 1,118 at the 2016 Census. In the early 1900s, the area was heavily mined for silver; the silver ore also contained cobalt. By 1910, the community was the fourth ...
;
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
and the Kootenay region of
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
; notably in the Boundary and "Silvery" Slocan. A silver rush in
Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
produced mines in an area known as Silver Valley, a handful of which are still active today. The first major silver ore deposits in the United States were discovered at the
Comstock Lode The Comstock Lode is a lode of silver ore located under the eastern slope of Mount Davidson, a peak in the Virginia Range in Virginia City, Nevada (then western Utah Territory), which was the first major discovery of silver ore in the Unit ...
in Virginia City,
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
, in 1859.


Environmental effects of historic silver mining

The amalgamation methods have proven problematic. It is estimated that 90% of the mercury consumed in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
from 1850 to 1900 was used to extract silver and
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
.Nriagu, Jerome, 1994.  Mercury pollution from the past mining of gold and silver in the Americas. Science of the Total Environment, Volume 149, Issue 3, Pages 167-181,ISSN 0048-9697, https://doi.org/10.1016/0048-9697(94)90177-5. An estimated 257,400 tonnes of mercury were lost to the environment in this process in the Americas since the patio process was first used. 60-65% of this is likely released into the atmosphere, being the single largest contributor to the global mercury cycle. Contaminants are also known to enter drinking water in and around abandoned silver mines. Well water in South Morelos State, Mexico, was found to have high concentrations of toxic metals including
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
,
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
,
manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...
,
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
, and
fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactiv ...
.Esteller, M.V., Domínguez-Mariani, E., Garrido, S.E. ''et al.'' Groundwater pollution by arsenic and other toxic elements in an abandoned silver mine, Mexico. ''Environ Earth Sci'' 74, 2893–2906 (2015). This is attributed to the abandoned and flooded silver mine at Huautla. Groundwaters flooded the mine-shafts after they were abandoned in the early 1990s, which allowed for
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
and mobilization of these dangerous contaminants.


See also

*
Silver mining in the United States Silver mining in the United States began on a major scale with the discovery of the Comstock Lode in Nevada in 1858. The industry suffered greatly from the demonetization of silver in 1873 by the Coinage Act of 1873, known pejoratively as the " Cr ...
*
Economic history of Spain This article covers the development of Spain's economy over the course of its history. Ancient era Iberians, roughly located in the South and East, and Celts in the North and West of the Iberian Peninsula were the major earliest groups in what ...
**
Global silver trade from the 16th to 19th centuries The global silver between the Americas, Europe and China from the sixteenth to nineteenth centuries was a spillover of the Columbian Exchange which had a profound effect on the world economy. Many scholars consider the silver trade to mark the ...
**
Spanish Empire The Spanish Empire ( es, link=no, Imperio español), also known as the Hispanic Monarchy ( es, link=no, Monarquía Hispánica) or the Catholic Monarchy ( es, link=no, Monarquía Católica) was a colonial empire governed by Spain and its prede ...
** Latin American economy **
Spanish treasure fleet The Spanish treasure fleet, or West Indies Fleet ( es, Flota de Indias, also called silver fleet or plate fleet; from the es, label=Spanish, plata meaning "silver"), was a convoy system of sea routes organized by the Spanish Empire from 1566 to ...
** Spanish Silver Train **
Royal fifth The royal fifth ( Spanish and pt, quinto real / quinto del rey) is an old royal tax that reserves to the monarch 20% of all precious metals and other commodities (including slaves) acquired by his subjects as war loot, found as treasure or extr ...
, 20% tax ** Patio process, invented in Mexico


References

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