Four stages [of the alchemical opus] are distinguished, characterized by the original colors mentioned in Heraclitus: melanosis (blackening), leukosis (whitening), xanthosis (yellowing), and iosis (reddening) … the xanthosis, otherwise called the citrinitas, gradually fell into disuse
Hillman launches his central argument by establishing Jung’s account of the four alchemical stages and foregrounding the historical suppression of xanthosis/citrinitas as the foundational problem the chapter will address.
, Alchemical Psychology, 2010thesis