Element · B

Boron

The element that makes glass survive thermal shock and neutrons stop moving.

Boron's contribution to borosilicate glass is a low coefficient of thermal expansion: the glass barely changes size when heated, so it does not crack when hot liquid meets a cold rim. Laboratory glassware and ovenware depend on this.

Separately, the boron-10 isotope absorbs neutrons better than almost anything else, which makes boron the standard material for reactor control rods and neutron shielding. Two entirely unrelated properties, both indispensable.

Uses

Boron's largest use is glass. Borosilicate glass — Pyrex and its equivalents — expands so little on heating that it survives thermal shock, and boron oxide is what makes glass fibre drawable for insulation and reinforcement.

Boron absorbs neutrons strongly, so boron carbide and borated steel are used in reactor control rods and shielding. Borax is a long-standing cleaning agent and flux for soldering, and boron is an essential plant micronutrient that appears in fertiliser blends.

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

Nuclear fuel — application · boron-10 absorbs neutrons better than almost anything, making it the standard control-rod material

is extracted from

Borax — mineral · the principal source of boron compounds Wikidata

is a component of

Neodymium magnet — alloy · 1–1.5% · about one per cent, and structurally essential — the compound is Nd₂Fe₁₄B, and without the boron it does not form

is produced by

Metallothermic reduction — process · magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely

is found in

Borosilicate glass — material · the element the glass is named for, and the whole of why it barely expands
Borax — 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 Boron 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

Boron → is produced by (magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely) → 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
Boron → is extracted from (the principal source of boron compounds) → Borax
Boron → is produced by (magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely) → 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
Boron → is produced by (magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely) → 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
Boron → is produced by (magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely) → 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
Boron → is produced by (magnesium reducing boron oxide, which gives an impure amorphous boron — the crystalline element needs a different route entirely) → 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. Boron can be traced through others besides.

Downstream — what it becomes

Boron → is a component of (about one per cent, and structurally essential — the compound is Nd₂Fe₁₄B, and without the boron it does not form) → Neodymium magnet → is used as (the strongest in commercial use, and the reason a motor, a hard drive and an earbud can be small) → Permanent magnets
Boron → is used as (boron-10 absorbs neutrons better than almost anything, making it the standard control-rod material) → Nuclear fuel
Boron → is a component of (about one per cent, and structurally essential — the compound is Nd₂Fe₁₄B, and without the boron it does not form) → Neodymium magnet → is used in (direct-drive wind turbine generators, which is what put rare-earth supply into energy policy) → Energy generation