Skip to content
Material World
Element · Os

Osmium

The densest naturally occurring element, and one whose oxide can blind you.

Osmium is the densest element known, marginally denser than iridium, and one of the least abundant in the crust. It is a hard, brittle platinum-group metal recovered from platinum and nickel refining residues.

It is also genuinely hazardous in a way most metals are not. Osmium tetroxide forms readily on the metal's surface in air, is volatile, and attacks the eyes and lungs at very low concentration. That toxicity, combined with brittleness, means the pure metal is rarely used and osmium is usually encountered as an alloying addition.

Uses

Osmium's uses exploit hardness and wear resistance in tiny quantities. Osmium-iridium alloys tipped fountain pen nibs, instrument pivots and phonograph styli — applications where a point must not wear away.

Osmium tetroxide, for all its hazard, is a valuable laboratory reagent: it stains fatty tissue for electron microscopy and catalyses a widely used reaction that adds two hydroxyl groups across a double bond. Osmium alloys also appear in electrical contacts and in some surgical implants.

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 sourced from

  • Platinum — element · from the residues of platinum refining
  • Nickel — element · and of nickel refining, where the platinum-group metals collect

is used as

  • Abrasive — application · osmium-iridium tips resist wear where a point must not blunt

is produced by

  • Electrorefining — process · the last of the platinum group to be separated, and produced in quantities measured in tonnes a year worldwide

is a component of

  • Osmiridium — alloy · 20–80% · one of the two densest elements known, and half of what makes the grains so resistant to wear

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 Osmium 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

  • Osmium → is sourced from (and of nickel refining, where the platinum-group metals collect) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → 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
  • Osmium → is sourced from (from the residues of platinum refining) → Platinum → is produced by (collected in the slimes, where the copper's own refining concentrates it) → Electrorefining → takes as input (as impure smelted anodes, around 99% copper, which is not pure enough for wire) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Osmium → is produced by (the last of the platinum group to be separated, and produced in quantities measured in tonnes a year worldwide) → Electrorefining → takes as input (as impure smelted anodes, around 99% copper, which is not pure enough for wire) → 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
  • Osmium → is sourced from (and of nickel refining, where the platinum-group metals collect) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Osmium → is sourced from (and of nickel refining, where the platinum-group metals collect) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (reduced with carbon to metallic tin) → Cassiterite
  • Osmium → is sourced from (and of nickel refining, where the platinum-group metals collect) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (reduced with coke in a blast furnace) → Hematite

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

Downstream — what it becomes

  • Osmium → is used as (osmium-iridium tips resist wear where a point must not blunt) → Abrasive
  • Osmium → is a component of (one of the two densest elements known, and half of what makes the grains so resistant to wear) → Osmiridium