They are a bit weak as far as other materials go for creating curiosities. Maybe thats good since its an infinite resource, but I feel like more dynamics could be added to give it more value. Since caves are getting biomes soon, and oceans are coming into play, I think this is a good time to add in new types of sand, glass, and curios. Maybe blue sand for caves. Would be neat to see it fit into the world generation! A way to crush sandstone into sand would be neat too, for really high Q sand later in the game when lower levels are being mined.
Not 100% on this, but I'm pretty sure shovels still don't affect the speed of digging up sand, and well thats just absurd.