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Material World
Element · Ba

Barium

A metal whose compounds are either lethal or routinely swallowed, depending entirely on solubility.

Soluble barium salts are acutely toxic. Barium sulfate is so insoluble that patients drink it before an X-ray, because it blocks the beam and passes through unabsorbed. The two facts are not in tension — they are the same fact, seen from either side of solubility.

That is the clearest illustration available of a principle that keeps recurring: toxicity is a property of a compound in a context, not of an element.

Uses

Barium's uses depend on being dense and on being insoluble. Barite — barium sulfate — is used in enormous tonnage as a weighting agent in oil and gas drilling mud, where its density holds down the pressure of the formation being drilled.

The same compound is swallowed as a contrast agent for X-ray imaging of the digestive tract: it blocks X-rays and is so insoluble that the body cannot absorb it, which matters because soluble barium compounds are seriously toxic. Barium carbonate is used in glass, ceramic glaze and ferrite magnets.

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 used as

  • Medical imaging — application · barium sulfate for gastrointestinal X-ray contrast

is extracted from

  • Baryte — mineral · the principal source of barium Wikidata

is produced by

  • Metallothermic reduction — process · aluminium reducing barium oxide under vacuum, the barium distilling off as vapour

is found in

  • Ferrite — material · in the hard grades — the cheap black ceramic magnets, which are most of the magnets in the world by unit
  • Baryte — mineral Wikidata

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
  • NIST — National Institute of Standards and Technology
    United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Barium 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.

Upstream — what it comes from

  • Barium → is produced by (aluminium reducing barium oxide under vacuum, the barium distilling off as vapour) → Metallothermic reduction → takes as input (the cheapest reducing metal and the commonest, and the aluminium in thermite) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (an early-crystallising constituent of basaltic magma) → Olivine
  • Barium → is extracted from (the principal source of barium) → Baryte
  • Barium → is produced by (aluminium reducing barium oxide under vacuum, the barium distilling off as vapour) → Metallothermic reduction → takes as input (reserved for halides and the most stubborn oxides, where the cheaper metals will not do the job) → Calcium → is produced by (from molten calcium chloride; there is no smelting route) → Molten salt electrolysis → takes as input (after concentration, as one of the two routes to lithium chloride) → Lepidolite
  • Barium → is produced by (aluminium reducing barium oxide under vacuum, the barium distilling off as vapour) → Metallothermic reduction → takes as input (the cheapest reducing metal and the commonest, and the aluminium in thermite) → Aluminium → is produced by (collects at the cathode while the carbon anodes are consumed) → Hall–Héroult process → takes as input (dissolved in molten cryolite and electrolysed) → Aluminium oxide → is sourced from (dissolved out with hot caustic soda in the Bayer process) → Bauxite
  • Barium → is produced by (aluminium reducing barium oxide under vacuum, the barium distilling off as vapour) → Metallothermic reduction → takes as input (the cheapest reducing metal and the commonest, and the aluminium in thermite) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (calcium-rich plagioclase is a defining constituent of basalt) → Plagioclase
  • Barium → is produced by (aluminium reducing barium oxide under vacuum, the barium distilling off as vapour) → Metallothermic reduction → takes as input (the cheapest reducing metal and the commonest, and the aluminium in thermite) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is sourced from (partial melting of mantle peridotite is what basalt magma is — the residue left behind stays peridotite, depleted of what went into the melt) → Peridotite

These are the most distinct paths back. Barium can be traced through others besides.

Downstream — what it becomes