Iron

Iron is a common refined metal used as a base industrial material and construction metal in Oxygen Not Included. It is produced from Iron Ore and appears naturally in several biomes and space locations. Iron serves as a primary input for Steel production, a usable construction material for mid- and late-game buildings and electrical components, a fuel for specific propulsion equipment, and a material component in certain Exosuit recipes.

Iron production is straightforward. The Metal Refinery refines Iron Ore into Iron at a 1:1 mass ratio; 100 kg Iron Ore → 100 kg Iron and requires Duplicant operation. Smooth Hatch herding offers an alternative conversion: a Smooth Hatch consumes roughly 100 kg Iron Ore and excretes about 75 kg Iron, providing a passive, if slower, method of producing Iron. The Rock Crusher can also convert Iron Ore into Iron, but at 50% efficiency: 100 kg Iron Ore → 50 kg Iron + 50 kg Sand, and is therefore less mass-efficient than the Metal Refinery.

Key uses and recipes involving Iron are concrete and quantifiable. Steel is made in the Metal Refinery from Iron, Refined Carbon, and Lime at the recipe 70 kg Iron + 20 kg Refined Carbon + 10 kg Lime → 100 kg Steel, and this process requires a Duplicant to operate the refinery. The Exosuit Forge can craft an Atmo Suit using Iron as an option in its recipe: 300 kg Aluminum or Copper or Iron + 2 units Reed Fiber → 1 Atmo Suit. The Solid Fuel Thruster burns Iron as fuel and each Solid Fuel Thruster consumes a fixed 400 kg Iron. As a Refined Metal, Iron is also suitable for building conductive wiring, advanced power systems, automation components, and various mid-game structures.

Sources and spawn locations: Iron occurs naturally in the Barren Biome and can appear in Meteor Showers in the Space Biome. Metallic Asteroids can contain Iron as well.

Practical notes and tips:

• Use Metal Refinery as the primary method to convert Iron Ore into Iron for best mass efficiency and throughput.
• Herd Smooth Hatches to passively convert ore into Iron if you can support their food and habitat needs; expect roughly 75% mass return.
• Avoid using a Rock Crusher for bulk Iron production unless you need Sand as a byproduct or have excess ore; its 50% conversion rate wastes mass.
• Iron is an economical choice for conductive wires and many mid-game structures; prefer it when Aluminum is scarce and when the structure does not require the lower thermal conductivity or lighter mass of other metals.
• Remember the Solid Fuel Thruster’s fixed 400 kg Iron burn requirement when planning mass budgets for rocket propulsion.