Pay dirt

	1.	(Mining) Earth, rock, etc., which yields a profit to the miner.
	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".

Noun	1.	pay dirt - ore that yields a substantial profit to the miner
	2.	pay dirt - a profitable success; "the inventor worked for years before hitting pay dirt"

ore