the whitened ‘body’ of the Stone also known as terra alba foliata (the ‘white foliated earth) whose ‘whiteness surpasses any snow in the world’… This is the pure matter from which the new Stone or ‘philosophical child is formed.
Abraham establishes snow as the primary alchemical image for the albedo stage, signifying the purified white matter from which the Philosopher’s Stone is reborn after the blackening of the nigredo.
, A Dictionary of Alchemical Imagery, 1998thesis