Mendip Hills In some areas the limestone and the dolomitic conglomerate have been mineralised with lead and zinc ores. From the time of Roman Britain until 1908, the hills were an important source of lead. These areas were the centre of a major mining industry in the past and this is reflected in areas of contaminated rough ground known locally as "gruffy". The word "gruffy" is thought to derive from the grooves that were formed where the lead ore was extracted from veins near the surface. Other commodities obtained included calamine (zinc ore), manganese, iron, copper and baryte. The eastern area reaches
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