I think it would be nice if there were different types of stones, which could be used in different ways. I suspect some form of chert is the generic stone. All stones except Anthracite would be used as normal stones.
The stones I have in thought are:
Granite, a hard rock, found in layer 3 down, with a quality of 50+ allowing for good stones and ores.
Gabbro, a very heavy, dense rock, contains large amounts of silver and gold, found in layer 4 down.
Diorite, an extremely hard rock, which could be used in some form of a weapon if rock weapons are added. Found in layer 2 down.
Marble, a soft, decorative rock which would be useful for carving into curiosities, paving decoratively, or making small statues to expand village borders. Found in the vicinity of mountains from layer 4 down.
Anthracite, the purest form of coal naturally available. It would be ready for use as fuel as soon as it was mined. Found in the vicinity of mountains from layer 1 down.