Philosofers stone / Latin: lapis philosophorum

The philosopher's stone (Latin: lapis philosophorum) is a legendary alchemical substance said to be capable of turning base metals (lead, for example) into gold or silver. 
It was also sometimes believed to be an elixir of life, useful for rejuvenation and possibly for achieving immortality. 

For many centuries, it was the most sought-after goal in Western alchemy. The philosopher's stone was the central symbol of the mystical terminology of alchemy, symbolizing perfection at its finest, enlightenment, and heavenly bliss. Efforts to discover the philosopher's stone were known as the Magnum Opus.