The Stonemason cuts rocks from a Stone Mountain and carries a piece of the rock to the Quarry where he lives. In the Quarry he will furtherly refine the piece of rock into smaller pieces. These pieces are called Stones. The Stonemason produces 3 Stones from one piece of rock.
It's useful to have 2-3 Stonemasons in your village, so you won't run out of Stones. If you run out of Stone you won't be able to build any houses etc. That means, if you run out of Stones, you have lost.
To train a Stonemason, you will need: