In internal alchemy, putrefaction or blackening is called The Dark Night of the Soul. If you're Gemini you probably get to go through it twice. A person doesn't have to ask, "Is this my dark night of the soul." it's very plan.
You will probably go through this stage whether you develop it with alchemy or not. It is easiest if you are a blunt, unpsychic, unimaginative, simple individual when going through this stage. Unfortunately, if you're reading these words, it won't apply to you -- you are imaginative and/or psychic. Externally it will appear to be a nervous breakdown. In a test tube, that is exactly what happens, the substance breaks down. The best thing to do during this stage is to get help. Without magickal intervention or understanding the step that comes next,you'll come out of this stage one of two ways:
Of course, a person in the stage of blackening is very susceptible to outside control (loss of personal power). They will accept about anything that will take away the pain. Workaholics can usually come out of this pretty well. Adolescent suicides are usually in the stage of blackening. If you think you missed it, think back to your teen-age years.