1 2 3 4 1 _ _ _ _ 2 _ _ _ _ 3 _ _ _ _ 4 _ _ _ _ ACROSS 1) not easy; requiring great physical or mental effort to accomplish or comprehend or endure 2) united states chemist who discovered deuterium (1893-1981) 3) excavation in the earth from which ores and ____rals are extracted 4) a number of sheets of paper fastened together along one edge DOWN 1) something that bulges out or is protuberant or projects from its surroundings 2) an elaborate song for solo voice 3) tear or be torn violently 4) a usually soluble substance for staining or coloring e.g. fabrics or hair ** Scroll down for solution. ** Are you sure you want to peek? hard urey mine pads