Element · As

Arsenic

A semi-metal known chiefly as a poison, and a serious contaminant of groundwater for millions of people.

Arsenic's reputation as a poison is deserved and historically well earned: it is tasteless, was readily available, and produced symptoms resembling natural illness. Its larger modern harm is unintentional. Naturally occurring arsenic in groundwater affects tens of millions of people, most severely in the Ganges–Brahmaputra delta, where tube wells drilled to escape surface-water pathogens tapped arsenic-bearing sediments instead.

Industrially it appears in semiconductors as gallium arsenide, and formerly in wood preservatives and pesticides.

Uses

Arsenic's uses are shaped by its toxicity, and most have been abandoned. Chromated copper arsenate preserved timber for decades and has been withdrawn from residential use in many countries; arsenical pesticides and pigments have gone the same way.

What remains is largely semiconductor chemistry. Gallium arsenide is used where silicon is too slow or cannot emit light — high-frequency amplifiers, laser diodes, LEDs and efficient solar cells. Small arsenic additions also harden lead alloys for cable sheathing and shot.

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

Lighting — application · as gallium arsenide, in infrared and laser diodes

is extracted from

Arsenopyrite — mineral · the main source, though it is recovered as an unwanted by-product of gold rather than mined for itself Wikidata

is produced by

Roasting — process · recovered as the trioxide from roasting arsenical ores, and reduced to the metal from that; the furnace yields the compound rather than the element

is sourced from

Copper — element · recovered from the flue gases of copper and lead smelting, where it is a contaminant to be captured rather than a product to be sought

is found in

Gallium arsenide — compound · exactly what it sounds like, which makes fabrication hazardous and the finished device entirely inert Wikidata
Arsenopyrite — mineral Wikidata
Cobaltite — mineral Wikidata
Sperrylite — 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

Where it comes from, and what it becomes

Follow Arsenic 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

Arsenic → is sourced from (recovered from the flue gases of copper and lead smelting, where it is a contaminant to be captured rather than a product to be sought) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
Arsenic → is produced by (recovered as the trioxide from roasting arsenical ores, and reduced to the metal from that; the furnace yields the compound rather than the element) → Roasting → takes as input (a copper sulfide; roasting drives off the sulfur that would otherwise prevent reduction) → Chalcopyrite
Arsenic → is extracted from (the main source, though it is recovered as an unwanted by-product of gold rather than mined for itself) → Arsenopyrite
Arsenic → is sourced from (recovered from the flue gases of copper and lead smelting, where it is a contaminant to be captured rather than a product to be sought) → Copper → is extracted from (the principal copper ore worldwide) → Chalcopyrite
Arsenic → is produced by (recovered as the trioxide from roasting arsenical ores, and reduced to the metal from that; the furnace yields the compound rather than the element) → Roasting → takes as input (roasted for its sulfur as much as for its iron) → Pyrite
Arsenic → is produced by (recovered as the trioxide from roasting arsenical ores, and reduced to the metal from that; the furnace yields the compound rather than the element) → Roasting → takes as input (roasted to the oxide, the sulfur going to an acid plant rather than the air) → Galena

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

Downstream — what it becomes

Arsenic → is used as (as gallium arsenide, in infrared and laser diodes) → Lighting