One of a group of specimens illustrating copper smelting - a sample of black glassy slag having much lime in it

One of a group of specimens illustrating copper smelting - a sample of common slag having quartz pieces which generally float on the surface and occasionally have copper with them

One of a group of specimens illustrating copper smelting - a sample of bad slag full of copper

One of a group of specimens illustrating copper smelting - a sample of slag showing copper suboxide

One of a group of specimens illustrating copper smelting - Napier's patent process - a sample of slag formed by fusing calcined powder

One of a group of specimens illustrating copper smelting - Napier's patent process - a sample of homogeneous slag from fusing ore and powder

One of a group of specimens illustrating copper smelting - Napier's patent process - a sample of crystallised slag from fusing calcined powder

One of a group of specimens illustrating the manufacture of malleable iron - a sample of puddling furnace slag

One of a group of specimens illustrating the manufacture of malleable iron - a sample of puddling furnace slag roasted, called bulldog slag, used for coating the hearth of the puddling furnace

One of a collection of raw and manufactured products from the Great Exhibition of 1851 - a sample of slag from coarse metal, illustrating J. Low's patent process from his copper works at Penclawdd

One of a collection of raw and manufactured products from the Great Exhibition of 1851 - a sample of slag from fine metal, illustrating J. Low's patent process from his copper works at Penclawdd

Sample of titaniferous slag from the Oakley Iron Furnaces near Dunfermline

Sample of copper slag, from the Bogoyavlensky Copper Mines, Government of Orenburg, Russia

Sample of copper slag, from the Bogoyavlensky Copper Mines, Government of Orenburg, Russia

Sample of copper slag, from the Bogoyavlensky Copper Mines, Government of Orenburg, Russia

Sample of copper slag, from the Bogoyavlensky Copper Mines, Government of Orenburg, Russia