<P> Mother lode is a principal vein or zone of gold or silver ore . The term is also used colloquially to refer to the real or imaginary origin of something valuable or in great abundance . </P> <P> The term probably came from a literal translation of the Spanish veta madre, a term common in old Mexican mining . Veta madre, for instance, is the name given to an 11 - kilometre - long (6.8 mi) silver vein discovered in 1548 in Guanajuato, New Spain (modern - day Mexico). </P>

Where did the term mother lode come from