Molten Pickaxe

The Molten Pickaxe can destroy most blocks in one hit. However, its mining speed is very slow, making it slower than Tungsten Pickaxe and above at mining the weakest block types. It is faster than most pre-Hardmode pickaxes when mining stones, excluding the Bone Pickaxe and Reaver Shark (except after 1.4.0.1). This stays true for harder blocks, such as Ebonstone and Crimstone. See the chart below for more details.

Trivia

 * The Achievement shows the Pre-1.4.0.3 sprite