A mythical alchemical substance that could allegedly transform base metals (most notably lead) into gold or silver. Depending on the source, it may also be a source of eternal life.

h4. Examples

* The Philosopher's Stone plays a major role in the plot of [[Fullmetal Alchemist]].

* One of [[Patchouli Knowledge]]'s Extra-stage [[spell card]]s in [[Embodiment of Scarlet Devil]] is "Fire Water Wood Metal Earth Sign "Philosopher's Stone".
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