Merriam-Webster Collegiate Dictionary - crucible

 noun  Etymology: Middle English corusible, from Medieval Latin crucibulum earthen pot for melting metals  Date: 15th century  1. a vessel of a very refractory material (as porcelain) used for melting and calcining a substance that requires a high degree of heat  2. a severe test  3. a place or situation in which concentrated forces interact to cause or influence change or development conditioned by having grown up within the ~ of Chinatown — Tom Wolfe