How can you tell the difference between an aluminium pot and a stainless steel one?

Take a grinder and grind one randomly-selected pot to dust. Snort the dust. If you suddenly develop symptoms of Alzheimer's, colic, rickets, extreme nervousness, anemia, headache, decreased liver and kidney function, forgetfulness, speech disturbances,and memory loss, softening of the bones, and weak, aching muscles, you're presenting aluminium toxicity symptoms and you're screwed. If you don't, you've got stainless steel, and you're going to be okay.