The Blue Gem mine, which is no longer active, produced almost every shade of green and blue turquoise imaginable. The Blue Gem mine site is located near Battle Mountain. It produced a great variety of turquoise, from intense blue to deep green combinations with a hard, irregularly distributed matrix. The Battle Mountain or Blue Gem mine, which began production in 1934 yielded the most valuable Blue Gem turquoise because of its rich color and hardness. Of the several Nevada mines that are named Blue Gem, this is the largest and most famous. Blue Gem turquoise tends to form in very thin slab forms rather than the typical nugget, although the largest nugget ever found weighed 178 pounds.