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
Metallic fiber (steel wool), bundle drawn from larger diameter wire (smallest fiber is produced by this method), cast from molten metal, or grown around a seed (often carbon). Bundle drawn metal fiber can be produced to sizes smaller than one micrometre in diameter. Currently metallic fibers are manufactured primarily in Europe with only three manufacturers still producing metallic yarn in the United States. Metlon Corporation is one of the remaining manufacturers in the U.S. that stocks a wide variety of laminated and non-laminated metallic yarns & Brightex Corporation, Japan and South Korea, such as Hwa Young, is also manufacturing Metallic fibers. China