So I found the location stone once in a dungeon and I nearly missed It. makes me wonder if there others I missed.

The place I found mine was in one of those seeker pits but it was one of those weirdly small seeker pits that wasn't deep and seemed like nothing was in it. Not sure if those are the only spots but yeah I was really lucky for some reason after passing it twice I decided to go into to the pit and even when I was in the pit I nearly missed it