‘Wolf rahm’: archaeological evidence for the veracity of an old term.
Tim Young and Sean Taylor.
Historical Metallurgy Journal Volume 49, Issue 2
The medieval tin smelting site at Brownie Cross, Devon, lies just 4km from the tungsten deposit of Hemerdon Ball and smelted alluvial ores commonly contaminated by wolframite. The slag is present as fragments of thin sheets, probably scraped from the surface of the tin in the float, the bases of which bear inclusions of tungsten metal, tin oxides, wolframite and hard head. The low-tungsten slags variously comprise spinels, ilmenite, olivine and Fe-cordierite in glass. The high-tungsten slags are glass with an unusual Fe-Mn-Mg tungstate (tungstate A) and commonly show relict emulsion textures, in which the tungsten-rich component shows extreme enrichment of tin with respect to silica. The ability of the tungsten-rich slags to capture tin demonstrates the problems faced by medieval smelters in Germany, who named the contaminant ‘Wolf rahm’ (wolf’s spit, foam, froth or dross), implying that the slag devoured tin, like a wolf devouring lambs.