transmutation

英[trænzmjuː'teɪʃ(ə)n;trɑːnz-;-ns-] 美[,trænsmjʊ'teʃən]

1. an act that changes the form or character or substance of something

2. a qualitative change

3. (physics) the change of one chemical element into another (as by nuclear decay or radioactive bombardment);

"the transmutation of base metals into gold proved to be impossible"