Skystone is a pale stone block found exclusively in the Promised Land dimension.
Skystone can be found under the topsoil of islands in the Promised Lands.
When mined with a pickaxe it drops Skystone Cobblestone, which can then be smelted to form Skystone. However, it is also possible to use the Silk Touch enchantment to mine Skystone directly. It's only crafting use is in Skystone Bricks