(n.) In mining, a rich mine or vein of silver or gold; hence, anything which is a mine of wealth or yields a large income.

Eldorado Golconda abundance affluence ample sufficiency ampleness amplitude avalanche bountifulness bountiousness bumper crop copiousness cornucopia eldorado extravagance exuberance fertility flood flow foison font fount fountain full measure fullness generosity generousness gold mine gravy train great abundance great plenty gush house landslide lavishness liberality liberalness lode lots luxuriance maximum mine mine of wealth more than enough mother lode much myriad myriads numerousness opulence opulency outpouring overflow plenitude plenteousness plentifulness plenty prevalence prodigality productiveness profuseness profusion quantities quarry repleteness repletion resource rich harvest rich lode rich uncle rich vein richness riot riotousness scads shower source source of supply spate spring staple stream substantiality substantialness superabundance teemingness treasure treasure trove treasury vein wealth well wellspring