High atop the Continental Divide, the Climax Mine opened during World War I to meet military needs for molybdenum, a metallic element that enhances the toughness and durability of steel. Climax became the most successful American company of the Great Depression, even as its workers cursed the mine as that hellhole near the sky. During World War II, Climax single-handedly supplied the huge Allied molybdenum demand, and in the postwar years became the world s largest underground mine. But in 1981, the molybdenum market crashed and caused devastating layoffs. For most of the next three decades, Climax remained on a care-and-maintenance status with only occasional and very limited production. But after a $750-million rebuilding program, the Climax Mine restarted in 2012 and is again a major source of the world s molybdenum. Steve Voynick s deft portrayal of Climax and its people, along with more than 100 rare photographs, make this updated edition of Climax: The History of Colorado s Climax Molybdenum Mine an invaluable contribution to western mining lore.