Vein of ore

• Profitable source
• Heston film of '82
• Gold seeker's target
• Rich source of anything
• Gold miner's bonanza
• Bonanza
• In the ___, there's the greatest concentration of ___

Wikipedia Word definitions in Wikipedia
Motherlode is an album by the American singer/songwriter Sara Hickman , released in 2006 . It is her first double album.

Wiktionary Word definitions in Wiktionary
n. 1 (context literally English) The main, central lode of a natural resource, near which smaller deposits of the same ore etc. exist. 2 (context figuratively English) The main prize, best cut or pick etc. by far, dwarfing all others.