Permafrosted stone

This could go along with a cave update, currently is very difficult to make something in the snow biome that is unique to the them of winter, u could make a cabin or a castle, or a mansion, but that's stuff u can make in any biome with trees, having a rock that is very icy in color would allow for all kinds of winter buildings especially if it is given the ability to be crafted into slabs, walls and stairs, it will inspire people to consider building in the snow biomes