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.
In some regions, various occupations might be exclusively staffed by members of a particular race or ethnic group. As examples, a city's butchers might tradtionally have orcish blood, or all the dwarves in an area could be expected to join the miners' guild (even if they personally have nothing to do with mining). Those who violate these stereotypes may find themselves in conflict with local customs or idiosyncratic laws.