Adamantite ore
Adamantite ore is an ore, which can be smelted in a furnace with 6 pieces of Coal to create Adamantite Bar with level 70 Smithing. Adamantite can be mined from adamantite rocks with level 70 Mining at in example Al-Kharid mines, but it's not recommended since it's too slow to be mined for good experience. You need pickaxe to be able to mine ores, which can be bought from Bob at the armory. Mithril Ore costs 400 coins from Bob and is the highest tier of ore that he sells.