This is a rare and magical substance which appears to be an ordinary, rather blackish and sooty piece of rock. It radiates a faint dweomer of indeterminate sort. 

If the stone is broken open, a geode-like cavity will be discovered. 

The interior of this cavity is lined with a quicksilver which will enable the transmutation of the base metals, iron and lead, into silver and gold. Either an alchemist or a magic-user will be required to effectuate such transmutation, however. From 50 to 500 pounds of iron can be made into silver, or from 10 to 100 pounds of lead can be turned into gold from a single philosopher's stone. Transmutation must be made fully upon the first attempt, all the quicksilver being employed at one time. 

Better still, there are two additional substances possible within such a stone. 

The first is a greenish, crystalline salt which will allow the manufacture of 1-4 potions of longevity; this substance has a 75% chance of occurring inside a given stone. 

The second is a pure white powder which, when admixed with a potion of longevity, can actually restore life to a dead human or demi-human if administered internally within one week of his or her demise (cf. raise dead spell). There is a 25% chance that the white powder will occur. 

Note that the experience-point value and gold piece sale value apply only to an unopened stone.