noun
: metallic copper of a black blistered surface, being the product of converting copper matte and being about 98.5 to 99.5 per cent pure — called also Bessemer copper
noun
: metallic copper of a black blistered surface, being the product of converting copper matte and being about 98.5 to 99.5 per cent pure — called also Bessemer copper
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012