Calamine brass a mixture of the virtually indistinguishable zinc ores smithsonite and hemimorphite) 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 zinc vapor to distill from the ores and permeate the metallic copper), contained a significant amount of slag 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 as cementation. Calamine brass was produced using proportions of two-sevenths
Christopher Schutz to mine and process the ore, being joined in some of their licences with Thomas Smythe, William Williams and Humfrey Cole. Only a few months later, in early 1566, William Humfrey and Schutz found calamine in the Mendip Hills, and Daniel Hoechstetter designed a refining process by which it could be used in Schutz' furnace at Tintern. As a reward for his work at Tintern, Schutz was granted denization on 9 April 1568, but the extraction of calamine ore at Worle Hill proved prohibitively expensive for the production of brass, and on 28 May the Company of Mineral and Battery