'Crucible' may trace to Latin 'crux' (cross) — its metaphor of a severe test comes from smelting heat.
A container in which metals or other substances are melted or subjected to very high temperatures; figuratively, a severe test or trial, or a situation in which different elements interact to produce something new.
From Medieval Latin 'crucibulum' (a melting pot, lamp, crucible), of disputed origin. The traditional etymology derives it from Latin 'crux' (cross), perhaps because early crucibles were marked with a cross, or because they were hung over a fire on a cross-shaped support. An alternative theory connects it to a Germanic source related to Old High German 'krūka' (pot, jug), which also gave English
Arthur Miller titled his 1953 play about the Salem witch trials 'The Crucible,' using the metallurgical metaphor to suggest that the trials were a fierce heat that tested the characters' integrity — some emerged purified, others were destroyed. The play was itself written as a crucible test of American values during the McCarthy era.