Meaning

noun a deposit of valuable ore occurring within definite boundaries separating it from surrounding rocks

originDoublet of load, which has however become semantically restricted. The now-archaic lode continues the old sense of Old English lād (“way, course, journey”) but by the 19th century survived only dialectally in the sense of “watercourse”, as a technical term in mining, and in the compounds lodestone, lodestar.

Etymology from Wiktionary, CC BY-SA 3.0