[Trexmaster]

I think it's been long enough that we can have Boulder items break down into a sub material that can be smelted into Boulders, much like all other ores that smelt into their Hard variants.

They could be Boulder Fragments. Or Pebbles if you wanted to be funny. Either way it just feels bad to drop a Boulder item that isn't desirable and have it breakdown into literally nothing.

It'd still take a fair few breakdowns worth to get enough boulders to fashion a material kit so I'd think it reasonable, considering how saturated the material list is.