Compressed coal block as fuel in furnance.
One compressed coal block can melt 800 items, the same as 10 vanilla coal blocks, which is very beneficial.
Compressed coal block
There is a texture for compressed coal block
Crafting a compressed coal block #2
New block recipe
Crafting a wither skull #1
Recipe using a compressed coal block
Crafting a wither skull #2
Recipe using a compressed coal block