mother lode
Originally meaning a main vein in mining, the spelling “motherload” is a mistake which is probably influenced by people thinking it means “the mother of all heavy loads.”
A “lode” was originally a stream of water, but by analogy it became a vein of metal ore. A vein of mineral ore deposited between clearly demarcated layers of rock ahdictionary dot com Miners of precious metals live to find a 'lode' of gold, which they refer to as a “mother lode,” often spelled as two words, sometimes as one (neither is in the dictionary though).
Definition paraphrased from Washington State University website
A “lode” was originally a stream of water, but by analogy it became a vein of metal ore. A vein of mineral ore deposited between clearly demarcated layers of rock ahdictionary dot com Miners of precious metals live to find a 'lode' of gold, which they refer to as a “mother lode,” often spelled as two words, sometimes as one (neither is in the dictionary though).
Definition paraphrased from Washington State University website
mother lode by Real GURU November 24, 2020
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