cobble

1. (geology) A particle from 64 to 256 mm in diameter, following the Wentworth scale.

2. (manufacturing) A piece of steel that becomes malformed during its manufacture or rolling.Examples: "These men are located near the rolls in a pulpit, which is usually completely inclosed with heavy close-meshed netting or boiler plate, so that if a cobble occurs they will be protected from the rods which fly in all directions on such occasions."; "The ideal control which they offer the reversing motor is such, when a cobble might be made in the steel mill, the metal can be handled gently, and very often the ingot saved."; "In practical mill work a roller often has to wait days and sometimes weeks before he can catch this condition, as he could not consider the stopping of production while he made a cobble in some particular roll pass that was giving him trouble, and it is mainly by studying the cobbles that the action of the steel can be observed and studied."