Mine, n.
 1. A subterranean cavity or passage; especially: (a) A pit or excavation in the earth, from which metallic ores, precious stones, coal, or other mineral substances are taken by digging; -- distinguished from the pits from which stones for architectural purposes are taken, and which are called quarries. (b) Mil. A cavity or tunnel made under a fortification or other work, for the purpose of blowing up the superstructure with some explosive agent.
 2. Any place where ore, metals, or precious stones are got by digging or washing the soil; as, a placer mine.
 3. (Fig.): A rich source of wealth or other good.
 Mine dial, a form of magnetic compass used by miners.
 Mine pig, pig iron made wholly from ore; in distinction from cinder pig, which is made from ore mixed with forge or mill cinder.
 gold mine (a) a mine where gold is obtained. (b) (Fig.) a rich source of wealth or other good; same as Mine 3.
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 Pig, n.
 1. The young of swine, male or female; also, any swine; a hog. “Two pigges in a poke.”
 2. Zool. Any wild species of the genus Sus and related genera.
 3.  An oblong mass of cast iron, lead, or other metal. See Mine pig, under Mine.
 4. One who is hoggish; a greedy person. [Low]
 Masked pig. Zool. See under Masked.
 Pig bed Founding, the bed of sand in which the iron from a smelting furnace is cast into pigs.
 Pig iron, cast iron in pigs, or oblong blocks or bars, as it comes from the smelting furnace. See Pig, 4.
 Pig yoke Naut., a nickname for a quadrant or sextant.
 A pig in a poke (that is, bag), a blind bargain; something bought or bargained for, without the quality or the value being known. [Colloq.]
 mine pig
      n : pig iron made entirely from ore