I know lava rock is cool and everything. In fact if I came to visit Iceland I would take a small piece home.
The whole place is made of lava, and recently, so there is a lot of lava rock.
But, for the last half an hour I have been sitting here at work watching tourists from China walk back and forth. They go out to the parking lot, pick up a bunch of rocks, then walk back to their rooms. Back and forth. Some of the rocks are pretty big. I guess all the friends back home are getting lava rock as a souvenir, but if they don't cut it out soon, the rock and tree gardens around the parking lot will be looking sparse and who wants to see what's under there?
I also have to wonder if they know about, or remember, the strict weight allowances on airlines.
It is fair to assume they flew here, it is an island.