The unity of the stone is the equivalent of individuation

Aion: Researches into the Phenomenology of the Self (Collected Works of C.G. Jung Vol.9 Part 2)

The unity of the stone is the equivalent of individuation, by which [we are] made one; we would say that the stone is a projection of the unified self.

This formulation is psychologically correct. It does not, however, take sufficient account of the fact that the stone is a transcendent unity.

We must therefore emphasize that though the self can become a symbolic content of consciousness, it is, as a supraordinate totality, necessarily transcendent as well.”

-Carl Jung, “The Alchemical Interpretation of the Fish,” in Aion: Researches into the Phenomenology of the Self