Pyrite is a mineral – you probably have heard of it as “fool’s gold”.

Is it harmful? Well, not if it’s lying around in rocks. Eating handfuls of pyrite is probably not a good idea. Context is important. In what context do you ask about it being harmful?

Iron disulfide
can be toxic

Pyrite is mined to make sulfuric acid and sulfur dioxide.

Can it end up in a house the same way Radon can? And some indication (its and, radon’s too) of its presence so that a lay person can go ahead ans call a Professional?

This is a question I heard, or read I can’t remember, but didn’t get to hear the answer.

….I meant “And Is there some indication of its (as well as Radon’s) so that a lay person can go ahead and call a professional?”