pay dirt

noun

1. soil, gravel, or ore that can be mined profitably.
2. Informal. any source of success or wealth; a fortunate discovery or profitable venture: After months of experimentation, the scientists finally hit pay dirt.
3. Football. end zone(def 1).

noun

1. a deposit rich enough in minerals to be worth mining
2. strike pay dirt or hit pay dirt informal to achieve one’s objective