One who enters sealed or abandoned mine shafts to explore or collect minerals and artifacts, generally under the cover of darkness.
Midnight miners had gained entry into the old Pewabic mine by using a 20 ton bottle jack to pry up the concrete cap.
by Toivo and Eino January 10, 2009
one who picks their nose in their sleep
he was great in bed but when we woke up I discovered he was a midnight miner
by rebelyid March 02, 2005