I have some missing tiles behind my sink cabinet and had to clean up some pile of crumbled material from this mortar. This is an old house but the bathroom tiles could have been remodeled since the 1980s. Does it seem to contain asbestos? I just found out it was used in some mortar mixes prior to the 1980s.
There's really only one way to tell with a building that is old enough that it might be there (and it "might" be in many things, whether or not it was common in those things.)
That way is to take a sample and send it to a laboratory for analysis.
I once got curious and looked into what that involves, and it's essentially some fancy microscope work that does not look particularly likely to be easily replicated by the home scientist.