Icestone is a terrain block added by the Aether II mod. It can be found most commonly in veins of 1–2, less commonly in veins of 5–6 and rarely, in veins of up to 10.
Its primary function is to freeze Water and Lava in a 7x7 square radius from the center, respectively into Ice and Obsidian. This function is not retained by its slab, wall and stair counterparts.
It can also be used to create Obsidian Armor and Obsidian Gloves, by surrounding a piece from the Pheonix Armor set/Pheonix Gloves with Icestone in a crafting table.
It requires a pickaxe with a mining level of 2 to mine.