Definition of blue lead in English:

blue lead

noun

US
Mining
historical
  • A gold-bearing stratum of bluish gravelly clay. Chiefly as the name (more fully "Great Blue Lead") of a particular lode in California.

Origin

Mid 19th century; earliest use found in Mining Magazine. From blue + lead.

Pronunciation

blue lead

/ˌbluː ˈliːd/