A template for materials! A material is a substrate. Due to the lack of any life at the moment, we're sticking to materials produced through non-living processes. Materials are not entirely formed from Elements, as if they were they would BE a fusion Element. For example, Immortal Peppermint, while frequently manifested as a solid, crystalline substance, is a fusion Element as it contains ONLY Elements (Woe and Phantom). Materials can be infused with one or more Elements, or none at all. They can also channel that Element's power as a conduit. The World Architect has a great library of preexisting materials, from slate to air to iron, so you don't have to make those yourself.
The material used as an example here is not canon.