Cupellation

When they are heated at high temperatures, the precious metals remain apart, and the others react, forming slags or other compounds.

This chemical reaction[9][10][11] may be viewed as The base of the hearth was dug in the form of a saucepan and covered with an inert and porous material rich in calcium or magnesium such as shells, lime, or bone ash.

By the Renaissance the use of the cupellation processes was diverse: assay of ores from the mines, testing the amount of silver in jewels or coins or for experimental purposes.

They used to be small vessels shaped in the form of an inverted truncated cone, made of bone ashes.

Ashes have to be ground into a fine and homogeneous powder and mixed with some sticky substance to mould the cupels.

Archaeological investigations as well as archaeometallurgical analysis and written texts from the Renaissance have demonstrated the existence of different materials for their manufacture; they could be made also with mixtures of bones and wood ashes, of poor quality, or moulded with a mixture of this kind in the bottom with an upper layer of bone ashes.

Archaeological findings of silver and lead objects together with litharge pieces and slag have been studied in a variety of sites.

[25] Mines such as Rio Tinto, near Huelva in Spain, became an important political and economic site around the Mediterranean Sea, as well as Laurion in Greece.

[26] Around 500 BC control over the mines of Laurion gave Athens political advantage and power in the Mediterranean so that they were able to defeat the Persians.

[21] Small-scale cupellation may be considered the most important fire assay developed in history, and perhaps the origin of chemical analysis.

Vannoccio Biringuccio,[30] Georg Agricola and Lazarus Ercker, among others, wrote about the art of mining and testing the ores, as well as detailed descriptions of cupellation.

By these times the amount of fire assays increased considerably, mainly because of testing ores in the mines to identify the availability of its exploitation.

Ethnoarchaeological and archaeological work in Porco Municipality, Potosí, Bolivia, has suggested pre-European use of huayrachinas.

Silver and lead artefacts have been found in the Peruvian central highlands dated in the pre-Inca and Inca periods.