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Material World
Mineral · Fe2O3

Hematite

Iron oxide — the most important ore of iron, and the red pigment used since the Palaeolithic.

Ore Pigment

Hematite is iron(III) oxide, and it does two very different jobs. Industrially it is the world's principal iron ore. Culturally it is red ochre, the pigment in the oldest surviving human art, and one of the few materials that connects Palaeolithic cave painting to a modern blast furnace.

How to identify it

The streak is diagnostic and unmistakable: hematite leaves a rust-red mark on unglazed porcelain regardless of what the specimen looks like. A black, metallic, mirror-bright crystal and a dull red earthy lump are both hematite, and both streak red.

Cultural significance

Red ochre is among the earliest materials humans deliberately sought out, transported and processed. Its use in burials across widely separated cultures is one of the earliest archaeological signals of symbolic behaviour.

How it forms

Hematite forms wherever iron meets oxygen, which is why it is the most abundant iron mineral at the Earth's surface. Its economically dominant occurrence is in banded iron formations, laid down when photosynthesis first put free oxygen into the oceans and precipitated the dissolved iron they had accumulated.

Those deposits record an event that happened once and cannot repeat, because the oceans no longer carry iron in solution. Hematite also forms by the oxidation of magnetite and other iron minerals during weathering, which is the source of the red colouring in a great deal of soil, sandstone and desert sand.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

contains

  • Iron — element Wikidata
  • Oxygen — element Wikidata

is an ore of

  • Iron — element · the most-used iron ore, though magnetite is richer Wikidata

is an input to

  • Smelting — process · reduced with coke in a blast furnace

is used as

  • Pigment — application · as red ochre

is commonly confused with

  • Magnetite — mineral · separated by the streak test: black versus red-brown

is a component of

  • Banded iron formation — rock · 20–60% · the iron oxide of the enriched ores, and what most of the world's iron is smelted from
  • Oxidised zone — deposit type · as the iron staining that makes a gossan visible from a distance — iron is what stays behind when everything else has gone into solution

is an alternative to

  • Baryte — mineral · as a drilling mud weighting agent, where the only property that matters is density per unit cost. Hematite is denser and more abrasive on pump parts, and baryte holds the market for that reason
  • Magnetite — mineral · as iron ore. Hematite ships direct at high grade where it has been weathered rich; magnetite is leaner and separates magnetically at low cost, which is what makes taconite worth mining at all — the choice is about the concentrator, not the metal

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Crystallography Open Database
    COD Advisory Board / Vilnius University · CC0 — contributors place data in the public domain

Questions this page answers

Where it comes from, and what it becomes

Follow Hematite back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Downstream — what it becomes

  • Hematite → is an input to (reduced with coke in a blast furnace) → Smelting → produces (as blister copper, refined electrolytically afterwards) → Copper → is a component of → Bronze → is used to make (cast in a two-piece mould with a core, which is what bronze does better than the copper it replaced) → Bronze socketed axe → is associated with → Bronze Age complete chain
  • Hematite → is an ore of (the most-used iron ore, though magnetite is richer) → Iron → is a component of → Steel → is associated with (produced in small quantities long before it could be made reliably) → Iron Age complete chain
  • Hematite → is used as (as red ochre) → Pigment
  • Hematite → is a component of (the iron oxide of the enriched ores, and what most of the world's iron is smelted from) → Banded iron formation
  • Hematite → is a component of (as the iron staining that makes a gossan visible from a distance — iron is what stays behind when everything else has gone into solution) → Oxidised zone
  • Hematite → is an ore of (the most-used iron ore, though magnetite is richer) → Iron → is a component of → Steel → is an input to (and the same steel becomes a spring, a cutting edge or a machinable bar depending only on the schedule) → Heat treatment → produces (laid up as fibre and resin and cured under heat and pressure, usually in an autoclave — and the cure schedule is as much of the specification as the fibre is) → Carbon fibre composite → is used as (aircraft primary structure since the 1990s, where stiffness per unit mass is what is being bought) → Structural engineering

These are the most distinct paths onward. Hematite ends up in others besides.