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Material World
Mineral · MnO2

Pyrolusite

Manganese dioxide — the main manganese ore, the black of cave painting, and the oxidiser inside a dry cell battery.

Ore Pigment

Pyrolusite is manganese dioxide, and it has been useful for longer than almost any other mineral. Ground to a powder it is a dense black pigment, and it appears in cave painting alongside the red and yellow ochres — the black in Palaeolithic art is very often manganese rather than charcoal.

Its industrial life is more recent and much larger. Nearly all manganese goes into steel, where it removes sulfur and oxygen during making and then contributes hardness and toughness to the finished metal. Steel without manganese is brittle at the hot-working temperature, so there is essentially no steel industry without this mineral.

Uses

Steelmaking takes the overwhelming share, as ferromanganese. A second use is electrochemical: manganese dioxide is the cathode material in the zinc-carbon and alkaline cells that have powered portable devices for a century, and it is there for the same property that makes it a pigment — it is a stable, cheap, strongly oxidising solid.

It is also used to decolourise glass, where manganese cancels the green cast that iron impurities give, which is why it was known to glassmakers as soap.

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.

is an ore of

  • Manganese — element · the principal manganese ore; nearly all of it goes to steel Wikidata

is used as

  • Battery electrodes — application · manganese dioxide is the cathode of the zinc-carbon and alkaline cells

is an input to

  • Smelting — process · reduced to ferromanganese, which is how nearly all manganese reaches steel

is a component of

  • Oxidised zone — deposit type · manganese oxide precipitated where dissolved manganese met air, and the commonest ore of the metal

contains

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 Pyrolusite 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

  • Pyrolusite → is an input to (reduced to ferromanganese, which is how nearly all manganese reaches steel) → 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
  • Pyrolusite → is an ore of (the principal manganese ore; nearly all of it goes to steel) → Manganese → is a component of (a fraction of a per cent, controlling grain structure) → Duralumin → is used as (aircraft structure, which it was developed for and dominated for half a century) → Structural engineering
  • Pyrolusite → is used as (manganese dioxide is the cathode of the zinc-carbon and alkaline cells) → Battery electrodes
  • Pyrolusite → is a component of (manganese oxide precipitated where dissolved manganese met air, and the commonest ore of the metal) → Oxidised zone
  • Pyrolusite → is an ore of (the principal manganese ore; nearly all of it goes to steel) → Manganese → is used as (present in essentially all steel, to remove oxygen and lock up sulfur) → Alloying
  • Pyrolusite → is an input to (reduced to ferromanganese, which is how nearly all manganese reaches steel) → Smelting → produces (as blister copper, refined electrolytically afterwards) → Copper → is a source for (much of world supply arrives as a by-product of copper mining rather than from cobalt-first operations) → Cobalt → is a component of (the balance, and both the reason it works hot and the reason it is expensive) → Samarium–cobalt magnet → is used as (weaker and untroubled by heat, which keeps it where temperature rather than strength is the constraint) → Permanent magnets

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