What is "ore hearth"

Ore \Ore\, n. [AS. [=o]ra; cf. [=a]r brass, bronze, akin to OHG. [=e]r, G. ehern brazen, Icel. eir brass, Goth. ais, L. aes, Skr. ayas iron. [root]210. Cf. Ora, Era.]

1. The native form of a metal, whether free and uncombined, as gold, copper, etc., or combined, as iron, lead, etc. Usually the ores contain the metals combined with oxygen, sulphur, arsenic, etc. (called mineralizers).

2. (Mining) A native metal or its compound with the rock in which it occurs, after it has been picked over to throw out what is worthless.

3. Metal; as, the liquid ore. [R.]
   --Milton.

   Ore hearth, a low furnace in which rich lead ore is reduced; -- also called Scotch hearth.
   --Raymond.

n. A low furnace in which rich lead ore is reduced.