sold from a bastok NPC usually because bastok controls Gustaburg Region most of the time. The NPC is located in port bastok, up the stairs near the Home Point Crystal.
also used to make Panacae, a level 98 Alchemy synth, which don't sell - but the platinum nuggets (alch96) made from Panacea do:
Light crystal,
philosopher's stone,
mercury,
sulfur,
rock salt.
