Cupellation
Cupellation is a
Since the
Process
Large-scale cupellation
Native
Lead melts at 327 °C, lead oxide at 888 °C, and silver melts at 960 °C. To separate the silver, the alloy is melted again at the high temperature of 960 °C to 1000 °C in an oxidizing environment. The lead oxidises to lead monoxide, then known as litharge, which captures the oxygen from the other metals present. The liquid lead oxide is removed or absorbed by capillary action into the hearth linings. This chemical reaction[9][10][11] may be viewed as
- Ag(s) + 2 Pb(s) + O
2(g) → 2 PbO(absorbed) + Ag(l)
The base of the hearth was dug in the form of a saucepan and covered with an inert and porous material rich in
Litharge cakes are usually circular or concavo-convex, about 15 cm in diameter. They are the most common archaeological evidence of cupellation in the
Small-scale cupellation
Small-scale cupellation is based on the same principle as the one done in a cupellation hearth; the main difference lies in the amount of material to be tested or obtained. The minerals have to be crushed, roasted and smelted to concentrate the metallic components to separate the
As the main purpose of small-scale cupellation was to assay and test minerals and metals, the matter to be tested must be carefully weighed. The assays were made in the cupellation or assay furnace, which needs to have windows and bellows to ascertain that the air oxidises the lead, as well as to be sure and prepared to take away the cupel when the process is complete. Pure lead must be added to the matter being tested to guarantee the further separation of the impurities. After the litharge has been absorbed by the cupel, buttons of silver were formed and settled in the middle of the cupel.[7] If the alloy also contained a certain amount of gold, it settled with the silver, and both had to be separated by parting.[17]
Cupels
The primary tool for small-scale cupellation was the cupel. Cupels were manufactured in a careful manner. They used to be small vessels shaped in the form of an inverted truncated cone, made of bone ashes. According to
History
The first known use of silver was in the
During the following
During the Roman times, the empire needed large quantities of lead to support the Roman civilization over a great territory; they searched for open lead-silver mines in areas they conquered. Silver coinage became the normalised medium of exchange, hence silver production and mine control gave economic and political power. In Roman times it was worth mining lead ores if their content of silver was 0.01% or more.[28]
The origin of the use of cupellation for analysis is not known. One of the earliest written references to cupels is Theophilus Divers Ars in the 12th century AD.[29] The process changed little until the 16th century.[21]
Small-scale cupellation may be considered the most important fire assay developed in history, and perhaps the origin of chemical analysis.
New World
The huge amount of
Some kind of blast furnaces called huayrachinas were described in colonial texts, as native technology furnaces used in
There are no specific archaeological accounts about silver
See also
- Alchemy
- Archaeometry
- Bottom-blown oxygen converter
- History of alchemy
- History of chemistry
- Philosopher's stone
References
- ^ Rehren, Th., Martinon-Torres, M, 2003
- ^ Bayley, J., Rehren, Th. 2007
- ^ Craddock, P. T. 1995
- ^ a b c d Bayley, J. 2008
- ^ a b c Rehren, Th., Eckstein, K. 2002
- S2CID 236973111.
- ^ a b c Hoover, H. and Hoover, H. 1950[1556]
- ^ a b Kassianidou, V. 2003
- ^ Craddock, P. T. 1995:223
- ^ a b Bayley, J., Crossley, D. and Ponting, M. (eds). 2008
- ^ Pernicka, E. et al, 1998
- ^ Bayley, J., Eckstein, K. 2006
- ^ Pernicka, E.,et al. 1998
- ^ Bayley, J. 2008: 134
- ^ Martinón-Torres, M., Rehren, Th. 2005a
- ^ Martinón-Torres, M. et al. 2009
- ^ a b Jones, D. (ed) 2001
- ^ Hoover, H. and Hoover, H. 1950 [1556]
- ^ Martinón-Torres, M. and et al. 2009
- ^ Craddock, P. T. 1991
- ^ a b c Martinón-Torres, M., Rehren, Th. 2005b
- ^ Pernicka, E. et al. 1998
- ^ Karsten H. et al., 1998
- S2CID 236973111.
- ^ Rehren, Th., Eckstein, K 2002
- ^ Tylecote, R.F. 1992
- ^ "Laurion and Thorikos". Retrieved January 15, 2010.
- ^ Tylecote, R.F., 1992
- ^ In Rehren, Th. 2003
- Martha Teach Gnudi, New York: The American Institute of Mining and Metallurgical Engineers, 1942, pp. 136-141
- ^ Van Buren, M., Mills, B. 2005
- ^ Howe, E., Petersen, U. 1994
Bibliography
- Bayley, J. 1995. Precious Metal Refining, in Historical Metallurgy Society Datasheets: https://web.archive.org/web/20160418021923/http://hist-met.org/hmsdatasheet02.pdf (accessed January 13, 2010)
- Bayley, J. 2008 Medieval precious metal refining: archaeology and contemporary texts compared, in Martinón-Torres, M and Rehren, Th (eds) Archaeology, history and science: integrating approaches to ancient materials by. Left Coast Press: 131-150.
- Bayley, J.,Eckstein, K. 2006. Roman and medieval litharge cakes: structure and composition, in J. Pérez-Arantegui (ed) Proc. 34th Int. Symposium on Archaeometry. Institución Fernando el Católito, CSIC, Zaragoza: 145-153. (PDF)
- Bayley, J., Rehren, Th. 2007. Towards a functional and Typological classification of crucibles, in La Niece, S and Craddock, P (eds) Metals and Mines. Studies in Archaeometallurgy. Archetype Books: 46-55
- Bayley, J., Crossley, D. and Ponting, M. (eds). 2008. Metals and Metalworking. A research framework for archaeometallurgy. Historical Metallurgy Society 6.
- Craddock, P. T. 1991. Mining and smelting in Antiquity, in Bowman, S. (ed), Science and the Past, London: British Museum Press: 57-73..
- Craddock, P. T. 1995. Early metal mining and production. Edinburgh: Edinburgh University Press.
- Hoover, H. and Hoover, H. 1950 [1556]. Georgius Agricola De Re Metallica. New York: Dover.
- Howe, E., Petersen, U. 1994. Silver and Lead in late Prehistory of the Montaro Valley, Peru. In Scott, D., and Meyers P. (eds.) Archaeometry of Pre-Columbian Sites and Artifacts: 183-197. The Getty Conservation Institute.
- Laurion and Thorikos (accessed January 15, 2010)
- Jones, G.D. 1980. The Roman Mines at Riotinto, in The Journal of Roman Studies 70: 146-165. Society for the promotion of Roman Studies.
- Jones, D. (ed) 2001. Archaeometallurgy. Centre for Archaeological Guidelines. English Heritage publications. London.
- Karsten, H., Hauptmann, H., Wright, H., Whallon, R. 1998. Evidence of fourth millennium BC silver production at Fatmali-Kalecik, East Anatolia. in Metallurgica Antiqua: in honour of Hans-Gert Bachmann and Robert Maddin by Bachmann, H. G, Maddin, Robert, Rehren, Thilo, Hauptmann, Andreas, Muhly, James David, Deutsches Bergbau-Museum: 57-67
- 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
- Lechtman, H. 1976. A metallurgical site survey in the Peruvian Andes, in Journal of field Archaeology 3 (1): 1-42.
- Martinón-Torres, M., Rehren, Th. 2005a. Ceramic materials in fire assay practices: a case study of 16th-century laboratory equipment, in M. I. Prudencio, M. I. Dias and J. C. Waerenborgh (eds), Understanding people through their pottery, 139-149 (Trabalhos de Arqueologia 42). Lisbon: Instituto Portugues de Arqueologia.
- Martinón-Torres, M., Rehren, Th. 2005b. Alchemy, chemistry and metallurgy in Renaissance Europe. A wider context for fire assay remains, in Historical Metallurgy: journal of the Historical Metallurgy Society, 39(1): 14-31.
- Martinón-Torres, M., Rehren, Th., Thomas, N., Mongiatti, A. 2009. Identifying materials, recipes and choices: Some suggestions for the study of Archaeological cupels. In Giumla-Mair, A. et al., Archaeometallurgy in Europe: 1-11 Milan: AIM
- Pernicka, E., Rehren, Th., Schmitt-Strecker, S. 1998. Late Uruk silver production by cupellation at Habuba Kabira, Syria in Metallurgica Antiqua : in honour of Hans-Gert Bachmann and Robert Maddin by Bachmann, H. G, Maddin, Robert, Rehren, Thilo, Hauptmann, Andreas, Muhly, James David, Deutsches Bergbau-Museum: 123-134.
- Rehren, Th.1996. Alchemy and Fire Assay – An Analytical Approach, in Historical Metallurgy 30: 136-142.
- Rehren, Th. 2003. Crucibles as reaction vessels in ancient metallurgy, in P.T. Craddock and J. Lang (eds), Mining and Metal Production through the Ages, 207-215. London. The British Museum Press.
- Rehren, Th., Eckstein, K 2002. The development of analytical cupellation in the Middle Ages, in E Jerem and K T Biró (eds) Archaeometry 98. Proceedings of the 31 st Symposium, Budapest, April 26 – May 3, 1998 (Oxford BAR International Series 1043 – Central European Series 1), 2: 445-448.
- Rehren, Th., Schneider, J., Bartels, Chr. 1999. Medieval lead-silver smelting in the Siegerland, West Germany. In Historical Metallurgy: journal of the Historical Metallurgy Society. 33: 73-84. Sheffield: Historical Metallurgy Society.
- Tylecote, R.F. 1992. A History of Metallurgy. Second Edition Maney for the Institute of Materials. London.
- Van Buren, M., Mills, B. 2005. Huayrachinas and Tocochimbos: Traditional Smelting Technology of the Southern Andes, in Latin American Antiquity 16(1):3-25
- Wood J. R., Hsu, Y-T and Bell, C. 2021 Sending Laurion Back to the Future: Bronze Age Silver and the Source of Confusion, Internet Archaeology 56. https://doi.org/10.11141/ia.56.9
External links
- Porco-Potosí archaeological project
- people.hsc.edu
- whc.unesco.org
- searchworks.stanford.edu
- gabrielbernat.es
- riotinto.com
- galileo.rice.edu
- Söderberg, A. 2011. Eyvind Skáldaspillir's silver - refining and standards in pre-monetary economies in the light of finds from Sigtuna and Gotland. Situne Dei 2011. Edberg, R. Wikström, A. (eds). Sigtuna.