I've been playing for 20-odd years, but always by ear. I'm only now starting to learn some theory. What I want to do is figure out the key of a song based on the chords it contains. This seems pretty easy most of the time, especially for standard blues-based rock. But what about stuff that isn't straightforward? My question is, if there's the occasional minor chord thrown in, does that mean the song is in a minor key, or is the minor chord just an accidental? Does this question even make sense? I don't even know enough theory yet to be dangerous. I do know that each major key has a relative minor associated with it, and I'm pretty sure the relative minor key shares the major's key signature. I also know the difference between major and minor scales. But beyond that.... TIA.