Wandering how to craft or get Blackstone in Minecraft when you’re unable to get that in Nether? Don’t worry, there is a behaviour pack for you “Blackstone to Basalt Converter“.
Unfortunately, you can not craft or make blackstone in any way as there is no such feature in the game,but now with this pack, you will be able to smelt the basalt to get the blackstone which is I think fine in the game as this is not a cheat thing, neither blackstone is such a precious thing so yeh! here is this addon/behaviour pack to smelt the basalt to get the black stone in minecraft bedrock edition.
Installation is very simple for this addon as the link given below is the direct link to download the file and the file is in .mcpack format, so you jsut need to download the file and just open it this will automatically install the behaviour pack in your game.
Same is the process for the Minecraft Pocket Edition
Remember this is a behaviour pack you will not see this addon in Global Resources in your game, create a new world and apply this from Behaviour Pack.