Iron(II) oxide
A black iron compound used as a pigment and found deep in the Earth
No single value: Iron(II) oxide is a material, and its colour varies. The background shows its family, black.
Iron(II) oxide is a black powder made from iron and oxygen, sometimes called ferrous oxide. Its mineral form is wüstite, and it is found in the Earth's mantle. The compound is used as a pigment, including in cosmetics and tattoo inks. It differs from rust, which is iron(III) oxide.
- Appears as a black powder
- Occurs naturally as wüstite
- Used as a pigment in cosmetics and tattoos
- Makes up about 9% of Earth's mantle
- Sometimes confused with rust
What colour is Iron(II) oxide?
Iron(II) oxide is a black-coloured compound made from iron and oxygen. It is sometimes mistaken for rust, but rust is a different iron oxide containing more oxygen and water. In nature, iron(II) oxide appears as the mineral wüstite. It is one of several oxides of iron and forms a powder that is often used as a pigment.
Where does Iron(II) oxide come from?
The name iron(II) oxide comes from its chemical makeup: iron in the +2 oxidation state combined with oxygen. The mineral wüstite is the natural form of this compound. It is found in the Earth's mantle, making up a notable portion of its composition.
How is Iron(II) oxide made?
This compound can be made by heating iron(II) oxalate, which breaks down to give iron(II) oxide, carbon dioxide, and carbon monoxide. The process is carried out without air to prevent forming other iron oxides. Another way to make pure iron(II) oxide is by heating a slightly iron-deficient version with metallic iron under high temperature and pressure.
Where Iron(II) oxide is used
Iron(II) oxide is used as a black pigment in art and cosmetics. It is approved for use in products applied to the skin, including tattoo inks. It is also used in aquariums to remove phosphates from the water.
Black around the world
What the black family means from country to country.
The black eagle gives the country its own name for itself: Shqiperia is commonly read as the land of the eagles.
Politics and protestPrideSource: AlbaniaBlack and yellow were the colours of the Habsburg monarchy. They come from the black double-headed eagle on a gold ground used by the Holy Roman Emperors.
Royalty and powerSource: Flag of the Habsburg monarchyThe black upper half of the Aboriginal flag stands for the Aboriginal people of Australia.
Politics and protestPrideSource: Australian Aboriginal flagOn 21 February, Language Martyrs' Day, people wear black badges and black and white clothes and walk barefoot to the Shaheed Minar to honour those killed in 1952.
Mourning and deathPolitics and protestGriefSource: Bengali language movementThe black, yellow and red of the flag come from the arms of the Duchy of Brabant: a gold lion with red claws and tongue on black. They were raised in the 1830 revolution.
Politics and protestPrideSource: Flag of BelgiumTwo diagonal stripes cross the yellow of the flag, one white and one black. They stand for the Sultan's two chief ministers.
Politics and protestSource: Flag of BruneiShades and relatives of Iron(II) oxide
Iron(II) oxide is part of a group of iron oxides, which include iron(III) oxide and magnetite. It is sometimes confused with rust, but rust is a hydrated form of iron(III) oxide. The compound can vary in its exact ratio of iron to oxygen, leading to a range of related forms.
Questions people ask about Iron(II) oxide
What colour is iron(II) oxide?
Iron(II) oxide is black in colour and is often found as a fine powder.
Where does the name iron(II) oxide come from?
The name refers to iron in the +2 oxidation state combined with oxygen. Its mineral form is called wüstite.
How is iron(II) oxide made?
It can be produced by heating iron(II) oxalate in an air-free environment or by treating a related compound with metallic iron under high temperature and pressure.
What is iron(II) oxide used for?
It is used as a pigment in art, cosmetics, and tattoo inks, and can also remove phosphates from aquarium water.
Is iron(II) oxide the same as rust?
No, rust is a hydrated form of iron(III) oxide, while iron(II) oxide is a different compound.
Good reading and sources
The facts on this page come from the Wikipedia article "Iron(II) oxide", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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