Storage Blocks are a type of material added by vanilla Minecraft and Thermal Foundation. They are the largest units of metal; one Block of metal is worth nine Ingots of the same metal. Vanilla Minecraft and Thermal Foundation add Block types for all of their metals and alloys.
Storage Blocks can be placed in the world. They rarely have a use in crafting, if at all; they are mostly a compact and/or decorative way to store metals and alloys.