Pyroclasm

Don't try this in survival mode...

Use this item to find the approximate distance to the nearest volcano

Hot basalt in various stages of cooling

Lava can flow a long distance, and will completely fill low areas it flows into

Volcano during late "mounding" stage. Lava pressure causes blocks to push up on world surface.

You won't want to stand this close in Survival Mode...

Cut Basalt, Basalt Cobblestone and Basalt Rubble (item)

Shortly after lava has broken through the top of the mound