mother lode

Etymology
Probably a.

Noun

 * 1)  A large or rich vein of gold or of another precious mineral from which other branches extend.
 * 2)  Any source of valuable or useful material.
 * 1)  Any source of valuable or useful material.

Translations

 * Dutch: hoofdader
 * Finnish: emosuoni
 * French: filon principal
 * German: Hauptader
 * Polish:, ,
 * Spanish: veta madre