Asphalt is a black building-block with a rough surface, different to the shiny block indicated on its icon. It can be crafted in your Crafting Menu (default key "Q") or at Crafting Tables (that still exist in worlds created before R22 on September 16th 2015), but only after the crafting-recipe has been unlocked upon taking a (block of) Fossils for the first time - which can be mined from the Fossil layer, requiring at least a Stone Mining Cell. Occasionally Fossils can also be obtained from Dustevils. To craft 8 (blocks of) Asphalt, you'll need (as of R24 in November 2015):