Wiktionary
mother lodes
n. (mother lode English)
Usage examples of "mother lodes".
Liath had heard other tales as well, speaking of goblins, small people, who lived in caverns deep underground, who mined the mother lodes, and who, perhaps, nourished themselves on human flesh.
Veins of gold like that are the original source of all the big nuggets that end up in placer pockets when the mother lodes are finally eroded away and washed by rain down into streams.
Before this time, even though it might point directly to the hidden mother lodes in any country, the taking of the gold would, of course, be blocked by the nation controlling the land.