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Material World
Element · Sr

Strontium

The red in fireworks, and an element whose radioactive isotope taught the world about fallout.

Pigment

Strontium salts burn a deep crimson, and no other element produces that red as cheaply, which is why strontium has been the standard red in pyrotechnics for two centuries.

Its other significance is grimmer. Strontium-90, a fission product, behaves chemically like calcium and is taken up into bone, where it stays. The discovery of strontium-90 in children's teeth during atmospheric nuclear testing was one of the more effective pieces of evidence in the argument for the 1963 test ban.

Uses

Strontium's most visible use is pyrotechnic: strontium salts produce the deep red of flares and fireworks, a colour no other cheap element gives cleanly.

Strontium carbonate was once consumed in quantity by the glass of cathode-ray television tubes, where it blocked X-rays generated by the electron beam — a use that vanished with the technology. Strontium ferrite makes inexpensive ceramic magnets. Strontium ranelate has been used to treat osteoporosis, exploiting the element's chemical similarity to calcium.

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

is extracted from

  • Strontianite — mineral · a source, though celestine supplies more of it Wikidata

is produced by

is found in

  • Ferrite — material · in the other hard grade, which has largely replaced the barium one on performance
  • Strontianite — 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 Strontium 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

  • Strontium → is produced by (the same aluminothermic route as barium, and in similarly small quantity) → 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
  • Strontium → is extracted from (a source, though celestine supplies more of it) → Strontianite
  • Strontium → is produced by (the same aluminothermic route as barium, and in similarly small quantity) → 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
  • Strontium → is produced by (the same aluminothermic route as barium, and in similarly small quantity) → 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
  • Strontium → is produced by (the same aluminothermic route as barium, and in similarly small quantity) → 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
  • Strontium → is produced by (the same aluminothermic route as barium, and in similarly small quantity) → 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. Strontium can be traced through others besides.

Downstream — what it becomes