Stone Bolts
The siege update brought the bolt throwers, which are great but go through a LOT of ammo. Either you burn through a prodigious amount of non-renewable metal bars, or you limit them to wood and bone bolts that feel like you’re shooting nerf darts. This mod is supposed to provide a middle option in-between the two extremes, something deadlier than wood, but cheaper to mass-produce than metal.
Firstly, at the Craftsdwarf shop you can make stacks of 25 bolts out of a boulder of Obsidian (igneous), Quartzite (metamorphic), or Chert (sedimentary). Stone bolts are made using the Stonecrafting labor. Quartzite and Chert were also given sharpness values (side effect: you can now make shortswords out of them the same as obsidian), so forts in non-igneous-extrusive regions should still have a decent chance at having at least some sufficiently sharp stones to work with.
Secondly, you can also make stacks of 10 bolts from raw glass chunks using the Gemcutting labor. With a magma Glass Furnace and access to sand this means you can make infinite ammo out of nothing but dwarf labor, but the tradeoff is that the small stack size makes them more work-intensive, both in the creation and for your siege engineers to load into the machines.
Lastly, you can also make arrows out of the same materials and in the same way, so bows are (somewhat) less useless should you come into possession of any.
All these materials, despite being quite sharp, are outclassed by any metal, even copper. They are however a marked improvement over wood or bone.
