Several different types of ore blocks can be mined from floating islands in the game.
The first ore you will find, and it is very abundant. Melting copper ore in a furnace yields bronze ingots, which is odd considering bronze is usually an alloy of copper and tin or arsenic.
Found nearly everywhere. Although a basic metal, iron retains its usefulness well into the game owning to it being a ingredient in many recipes both in its base form and as steel. Because of this it is advisable to gather and melt all iron ore found, however since steel cannot be reverted back to iron nor can iron be always substituted for steel and some recipes specifically need iron, it is a good idea not to convert all iron into steel.
Grey-blue and can be found in the upper third of the world. Like all of the other base metals, it can be smelted into titanium ingots without needing a recipe. This makes it possible to mine and use titanium from the start when the player gains access to an airship, unlike adamantium, mining which is restricted by poisonous gas. Titanium is slightly stronger than steel, and significantly lighter. This makes it an ideal material for an airship hull. Titanium propellers are also the most efficient propellers available until late-game. Most noticeably titanium cannot be used to make engines.
Purple in color and can be obtained in ore form as loot from killing Kraken, or mining in the lower third of the world. This metal is highly resistant to physical damage, but is heavy, with a placement mass of 0.5.
A vivid, violet colored ore. Can be found in the upper third of the world. Heartstone ore cannot be mined in the traditional sense, but medium and large meteor's will leave behind Heartstone ore when they impact an object. Heartstone cannot be smelted into ingots in its raw form, but can be crafted into Refined Heartstone and sold for a good profit.
Brown colored block with flecks of light blue. Diamond cannot be used to create ingots, and is used for specialty item recipes.