I think the mystical experience and alchemy are inseparable, in-so-far as you include the term "mystical" to include the involvement of forces which are subject to conscious actors which are indispensable to perform alchemy, whether or not the practitioner knows it or not. The Stone can only be made by art, so to speak, and the art lies in identifying these subtle forces, capturing them successfully, and then using them correctly. It's an interplay between man and nature that requires man to know nature sufficiently well enough to manipulate it. It can't occur without knowledge, which is itself subject to consciousness. In a roundabout way, all mysticism has to deal with consciousness and perception, and it's via the broadening and refinement of consciousness that anything of note can be accomplished. You could say this is true of any field, be it science or mysticism. Of course, Hermeticism is called a sacred, or divine, science, so take that as you will.