'Pay rock' definitions:

Definition of 'Pay rock'

From: GCIDE
  • Pay dirt \Pay dirt\, Pay rock \Pay rock\, etc.
  • 1. (Mining) Earth, rock, etc., which yields a profit to the miner. [Western U. S.] [Webster 1913 Suppl.]
  • 2. a discovery, especially after an exploratory process, which yields a profit or sought-after benefit; -- used especially in the phrase "to hit pay dirt". [PJC]