| bonanza(noun, source, pit, vein, excavation) |
| source of supply(noun, expression, idiom, source) |
| vein(noun, source, pit, excavation, coalfield) |
| mine(noun, supply, deposit, pit, excavation) |
| mine of wealth(expression, idiom) |
| mother lode(noun, source) |
| cash cow(noun, expression, hit, source, success) |
| colliery(noun, pit, excavation, coalfield, coalmine) |
| fount(noun, pit, excavation, coalfield, coalmine) |
| fountain(noun, pit, excavation, coalfield, coalmine) |
| gravy train(noun, source) |
| lode(noun, pit, excavation, coalfield, coalmine) |
| pit(noun, excavation, coalfield, coalmine) |
| quarry(noun, pit, excavation, coalfield, coalmine) |
| rich lode(noun, source) |
| shaft(noun, pit, excavation, coalfield, coalmine) |
| source(noun, pit, excavation, coalfield, coalmine) |
| spring(noun, pit, excavation, coalfield, coalmine) |
| treasure trove(noun, expression, pit, excavation, windfall) |
| treasury(noun, pit, excavation, coalfield, coalmine) |