Quartz Slabs seem to have the minecraft:stone_slab ID

Don't actually know if it's a bug or not, but Quartz Slabs seem to have the minecraft:stone_slab ID, so I cannot spawn them in with Command Blocks or the like. Could be that it's just a different Stone Slab ID, but I find that unlikely since Quarts Stairs, Blocks and the like are all "minecraft:quartz_".