* Water: Lava is molten rock, and water is the opposite in its state of matter.
* Ice: This emphasizes the contrast between hot, flowing lava and cold, solid ice.
* Solid rock: Lava is liquid, while solid rock is its opposite in form.
* Sediment: Lava is formed from melted rock, while sediment is broken down rock.
* Cool: This describes the temperature difference, as lava is extremely hot.
The best word to use will depend on the specific situation and what aspect of lava you want to contrast.