The Pan amalgamation process is a method to extract silver from ore. Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen The process was widely used from 1609 through the 1800s; it is no longer used.
The patio process had been used to extract silver from ore since its invention in 1557. The patio process was a process used to extract Silver from ore Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen One drawback of the patio process was the long treatment time, usually weeks. Alvaro Alonso Barba invented the faster pan process (in Spanish the cazo or fondo process) in 1609 in Potosí, Bolivia, in which ore was mixed with salt and mercury (and sometimes copper(II) sulfate) and heated in shallow copper vessels. Alvaro Alonso Barba was a secular Catholic priest and Metallurgist. Potosí is a city the capital of the department of Potosí in Bolivia. The Republic of Bolivia (República de Bolivia) named after Simón Bolívar, is a Landlocked country in central South America. Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 The treatment time was reduced to 10 to 20 hours. Whether patio or pan amalgamation was used at a particular location often depended on climate (warmer conditions speeded the patio process) and the availability and cost of fuel to heat the pans. 
The amount of salt and copper(II) sulfate varied from one-quarter to ten pounds of one or the other, or both, per ton of ore treated. Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 The loss of mercury in amalgamation processes was generally one to two times the weight of silver recovered. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen
The Washoe process, a variation of pan amalgamation, developed in the 1860s to work the ore from the Comstock Lode in Nevada (before becoming a territory, Nevada was popularly known as Washoe). The Comstock Lode was the first major US deposit of Silver Ore, discovered under what is now Virginia City Nevada on the eastern slope of Mt Nevada ( is a state located in the western region of the United States of America. In the Washoe process, the copper pans were replaced by iron tanks with mechanical agitators. Each pan was circular, and commonly held 1,200 to 1,500 pounds ore that had been crushed to sand size. Water was added to make a pulp, and 60 to 70 pounds of mercury, along with one-half to three pounds each of salt (sodium chloride) and bluestone (copper(II) sulfate) were also added. For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Copper(II sulfate is the Chemical compound with the formula Cu[[Sulfur S]] O 4 A circular iron plate called a muller was mounted on a vertical shaft and lowered into the pan, and was rotated to provide both agitation and additional grinding. Heat was delivered to the pans by steam pipes. 
A variation of the Washoe process was developed in the Reese River mining district around Austin, Nevada. Austin is a small unincorporated community located in Lander County Nevada, in the United States. The Washoe process was found not to work well for ores with arsenic or antimony sulfides, or with galena or sphalerite. Arsenic (ˈɑrsənɪk is a Chemical element that has the symbol As and Atomic number of 33 Antimony (IPA (Received Pronunciation, /ˈæntɪmoʊni/ (US is a Chemical element with the symbol Sb (stibium meaning "mark" and The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation Galena is the natural mineral form of Lead sulfide. It is the most important Lead Ore mineral Sphalerite (( Zn, Fe) S) is a Mineral that is the chief Ore of Zinc. In 1869, Carl A. Stetefeldt of Reno, found that roasting the ore with salt converted the silver sulfides to silver chlorides, which could then be recovered in amalgamation pans.  The process was introduced in the Reese River District in 1879, with great success.
Other silver-mining districts using the Reese River process included Georgetown, Colorado, Caribou, Colorado, and Silver Cliff, Colorado. The historic Town of Georgetown is a Territorial Charter Municipality that is the County seat of Clear Creek County, Colorado, United Caribou is a former silver-mining town now a Ghost town near Nederland in Boulder County, Colorado, United States. Silver Cliff is a Statutory Town that is the most populous town in Custer County, Colorado, United States.