Mother lode singular noun countable noun
A main vein of a mineral in a given area
They failed to find the mother lode of gold.
A large quantity of something
Oh! You are so lucky today with a basket full of fish. You hit the mother lode!.
Her personal life experiences have given her a mother lode of material for her current job.
Adequate measures or actions
"Mother lode" was originally an American mining word that referred to the primary vein of ore in a region from 1855 to 1860, but it is now commonly used figuratively to refer to any plentiful supply of something.