 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Calamine brass" – news ·newspapers ·books ·scholar ·JSTOR(March 2025) (Learn how and when to remove this message) |
Calamine brass isbrass produced by a particularalloying technique using thezincorecalamine directly, rather than first refining it to metallic zinc. Directzinc smelting appears to have been unknown in Europe until the mid-18th century, even though the alloyed calamine brass was in use for centuries, and metallic zinc was produced directly viareducing-atmosphere smelting in India and China from the 12th century CE onwards.
Brass is an alloy ofcopper andzinc and, when it was first developed, methods for producing metallic zinc were unknown.Metallurgists wishing to produce brass thus used calamine (actually a mixture of the virtually indistinguishable zinc oressmithsonite andhemimorphite) as the zinc component of brass. The resulting brasses, produced by heating a mixture of copper and calamine to a high temperature for several hours (allowing zincvapor to distill from the ores and permeate the metallic copper), contained a significant amount ofslag material resulting from the non-zinc components of calamine. The use of ore rather than metallic zinc also made it difficult to accurately produce the desired final proportion of copper to zinc. This process is known ascementation.
Calamine brass was produced using proportions of two-sevenths finecopper, four-sevenths calamine, and one-seventh shruff (old plate brass). Calamine brass was the first type of brass produced, probably starting during the 1st millennium BC, and was not replaced inEurope by other brass manufactures until the 18th century. It is likely thatIndian brass manufacturers had developed more advanced techniques some centuries earlier.[citation needed]
The area around La Calamine, nowKelmis, inBelgium, was the source of much of the medieval brass of northern Europe. Brass production was introduced to England in 1587 when several members of theCompany of Mineral and Battery Works obtained a licence from the company (within whose monopoly it was) to build a brass works atIsleworth. However a decade later the company obstructed the owners from mining calamine. A plaque atTintern Abbey claims that the well-known brassworks at this site began in 1568.[note 1][note 2]
New brass works were built by a German immigrant in 1649 atEsher, probably usingSwedish copper. After the passing of theRoyal Mines Act 1688 (1 Will. & Mar. c. 30), further works were built nearBristol, where brass production became a major industry in the 18th century.[1][2] Later brass production sites in England includedCheadle andBirmingham.
Calamine brass was slowly phased out as zincsmelting techniques were developed in Europe, which produced metallic zinc more suitable for brass production than calamine. However, the conversion away from calamine brass manufacture was slow; aBritishpatent was awarded toWilliam Champion in 1738, but the alloying of metallic zinc and copper to produce brass was not patented until 1781 (by James Emerson), and calaminebrass mills persisted inSouth Wales until as late as 1858. The slow diffusion of this technology was probably the result of economic factors.