Mining

The twentieth entry is a escória, and English owns the same word without ever using it for this. Behind both stands the Greek skōria, the dross a metal throws off, which the Greeks built on skōr, dung: what the furnace passes. Latin took it over as scoria, and from there it went into Portuguese as a escória and into English as « scoria ». But « scoria » never settled in the foundry. It was drawn off into geology instead, and today it names the cindery, gas-bubbled rock a volcano throws out; a metallurgist who used it of a blast furnace would be understood and would sound like a textbook. For the thing itself English reached for a Germanic word, « slag », out of Middle Low German slagge, the bits that fly off when something is struck. So one language names the grey heap beside the furnace after what the fire rejects and the other after the blow of a hammer, and a reader who knows a escória already knows an English word — just not the one the smelter uses.