goaf

POS

Noun

top

CIDE DICTIONARY

goaf, n. [Cf. 1st Gob.].

That part of a mine from which the mineral has been partially or wholly removed; the waste left in old workings; -- called also gob . [1913 Webster]

To work the goaf or To work the gob, to remove the pillars of mineral matter previously left to support the roof, and replace them with props. Ure.