Black dust keeps appearing in streaks on my floor

It's in the master bedroom. I vacuumed it up the first time, and waited a couple months for it to appear again in the exact same pattern. It looks kind of like soot, but I can't for the life of me think of where it would come from. It almost looks like it's blowing out from the floorboards.

It's in the master bedroom. I vacuumed it up the first time, and waited a couple months for it to appear again in the exact same pattern. It looks kind of like soot, but I can't for the life of me think of where it would come from. It almost looks like it's blowing out from the floorboards.