Search Results: should break it off

So I have two really good chairs at work. One, I brought from home, and the other I actually ordered myself online. I was using the older chair until the new one arrived and then, I put my older chair in the break room.

Both chairs are not cheap; they are large high-end "board executive" chairs, which in US currency, would be about $150. But the older one was used and someone gave it to me. The older chair was in the break room and I still used it, about every other day, although the break room is mostly empty.

Today, some coworker dude took my chair. I had to track it down and found it in his classroom. This is a teacher from another department, who teaches high schoolers, so even though we work in the same place, I don't even know this guy's name.

I confronted him about it, and he said he asked our boss about it, who didn't know who it belonged to (which is accurate; he's too busy to know such things) before taking it, assuming it "belonged to no one" or an old coworker who was no longer here. I told him it was mine, and he could use it, but to just make sure not to break it or mistreat him.

However, I don't really want him using my sh*t. There are MANY different chairs in here, most of which are simple student wooden chairs. There's also some basic blue office chairs in here too, which are kind of crap. And some used office chairs.

The chair is already kinda old, so I think he'll end up breaking it.

But it's also a spare chair, as I bought a newer one in October. I still used it in the break room, but that's not all that important.

And he didn't ask to use it, although that may have just been ignorance on his part. But there are literally other chairs he could use around here, just none as nice.

How should I handle this admitted first-world problem?