An arrastra (or arastra) is a primitive
mill
Mill may refer to:
Science and technology
*
* Mill (grinding)
* Milling (machining)
* Millwork
* Textile mill
* Steel mill, a factory for the manufacture of steel
* List of types of mill
* Mill, the arithmetic unit of the Analytical Engine early ...
for grinding and pulverizing (typically)
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
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 ...
ore. Its simplest form is two or more flat-bottomed drag stones placed in a circular pit paved with flat stones, and connected to a center post by a long arm. With a horse, mule or human providing power at the other end of the arm, the stones were dragged slowly around in a circle, crushing the ore.
Some arrastras were powered by a
water wheel
A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
; a few were powered by steam or gasoline engines, and even electricity.
[
Arrastras were widely used throughout the ]Mediterranean region
In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and wa ...
since Phoenicia
Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their his ...
n times.[ The ]Spanish
Spanish might refer to:
* Items from or related to Spain:
**Spaniards are a nation and ethnic group indigenous to Spain
**Spanish language, spoken in Spain and many Latin American countries
**Spanish cuisine
Other places
* Spanish, Ontario, Can ...
introduced the arrastra to the New World
The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...
in the 16th century. The word "arrastra" comes from the Spanish language
Spanish ( or , Castilian) is a Romance language of the Indo-European language family that evolved from colloquial Latin spoken on the Iberian peninsula. Today, it is a global language with more than 500 million native speakers, mainly in the ...
''arrastrar,'' meaning to drag along the ground.[ Arrastras were suitable for use in small or remote mines, since they could be built from local materials and required little ]investment capital
In economics, capital goods or capital are "those durable produced goods that are in turn used as productive inputs for further production" of goods and services. At the macroeconomic level, "the nation's capital stock includes buildings, ...
.
For gold ore, the gold was typically recovered by amalgamation with quicksilver. The miner would add clean mercury to the ground ore, continue grinding, rinse out the fines, then add more ore and repeat the process. At cleanup, the gold amalgam was carefully recovered from the low places and crevices in the arrastra floor. The amalgam was then heated in a distillation retort to recover the gold, and the mercury was saved for reuse.[
For silver ore, the patio process, invented in Mexico in 1554, was generally used to recover the silver from ore ground in the arrastra.
]
References
External links
*
Arrastra
at Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various t ...
{{Extractive metallurgy
History of mining
History of metallurgy
Mining equipment
Grinding mills