Stones that have been attuned to the extreme temperatures of deserts or icy wastes. Such stones are quite valuable to adventurers as they can use them in order to preserve or prepare meals, make extreme environments bearable, and use them in clever devices.
There are those as rich as kings but dress as peasants and worry not about funding. To visit their true homes one would see wealth of untold value scattered as dirt is in a hut. They know the monetary value of their possessions but they have long lost any true value to their owners. Experience is their currency and their curse. They dispense secrets of the ages as if discussing the weather. Few things have they not experienced so that very little gives them joy. They are the lost ones looking for new life while humoring the mortals around them.