original Middle English spelling of load (n.), and custodian of most of the original meaning of "way, course, carrying." Differentiation in sense took place 16c. Mining sense of "vein of metal ore" is from c.1600, from notion of miners "following" it through the rock.
in geology, ore body that is disseminated within definite boundaries in unwanted rock or minerals (gangue). The term, as used by geologists, is nearly synonymous with the term lode, as used by miners. There are two distinct types: fissure veins and ladder veins.