Has anybody figured out what to do with the index card and the rune stone? I've managed to get the stone to glow but don't know where to put it or what to apply it to. And the description for the index card gives me the prompt, "Some kind of index card - but for what?" which seems to suggest it also has a specific use, but what could that be?

Lovely game regardless, but it bothers me that I can't figure these two things out...

ETA: Replayed and tried all sorts of actions with these items; so far no results. Unfortunately they also both have a tendency to fall through the floor and become irrecoverable if you drop them in the wrong place...