Falling Icicles Should Turn Lava into Obsidian

With the new ice caves coming to the game, it would be a highly logical and rewarding mechanic if falling icicles interacted directly with lava. Currently, water and ice blocks cool down lava. If a player or an explosion causes an icicle to break and fall from the ceiling directly into a lava source block, the freezing impact should instantly cool that lava block and turn it into obsidian (or cobblestone for flowing lava). This would add a great layer of environmental interaction to the new caverns. It gives players a strategic, creative way to safely clear out dangerous underground lava pools by utilizing the natural hazards around them.