mother lode
From Longman Dictionary of Contemporary EnglishRelated topics: Earth sciences, Industrymother lodeˈmother lode, motherlode /ˈmʌðələʊd $ -ðərloʊd/ noun [countable usually singular] American English 1 HETIa mine that is full of gold, silver etc2 LOT/LARGE NUMBER OR AMOUNTa place where you can find a lot of a particular type of objectmother lode of The Sharper Image catalog is a mother lode of men’s gadgets and toys.3 → hit the mother lodeExamples from the Corpusmother lode• The region is a mother lode of potential support for his candidacy.