Stainless steel works very well, make sure it is non magnetic, this will be the most durable; if I am incinerating on a fire and hot coals this is my choice.
I also like to use the white square corning ware type casserole dish,
Or the amber or purple type stove top skillet vision ware or Pyrex type,
I am not sure that I got the names of this right; they hold up very well to my hot plate and torch, do not change temperature fast.
One reason I like these also is that I can also heat with acids, rinse, neutralize, decant, heat dry, incinerate, add water and acid, and so on, without taking the materials out of the pot.
Normally you want to expose your material air, but having a lid is also very useful, when trying to keep out dirt debris, when things bubble, pop and splash, or snow or rain become a problem.
