lode

noun

1. (obsolete)A way or path; a road.
2. (dialectal)A watercourse.
3. A vein of metallic ore that lies within definite boundaries, or within a fissure.

   “The metals traditionally sought in the Bristol Bay region have been gold and copper, mostly in deposits near Lake Iliamna. An exception is a gold lode discovered about 1930 near Sleitat Mountain (4), where about $200 in gold was recovered from small quartz veins near the periphery of a small granitic intrusive body.”

4. (broadly)A rich source of supply.

   “In recent years, Jack Grieve of the department of English and linguistics at the University of Birmingham in England has embraced Twitter as a bountiful lode for looking at language-use patterns.”