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Material World
Mineral · CoAsS

Cobaltite

A cobalt arsenic sulfide — the mineral that gave cobalt its name, from the goblin miners blamed for the poison it gave off.

Ore

Cobaltite is a sulfarsenide of cobalt, and it is the source of the element's name. German miners found ore that looked like silver, yielded none, and released arsenic fumes when roasted; they blamed a goblin, the *kobold*, and the name stuck to the metal when it was finally isolated.

That history is a real property rather than a story. Cobalt minerals commonly carry arsenic, and roasting them is genuinely dangerous — the difficulty of the ore is why cobalt was recognised as a pigment for centuries before anyone extracted the metal.

How to identify it

Silver-white to steel-grey with a pink cast, metallic, and hard for a sulfide at 5.5 to 6. It commonly forms sharp cubes and pyritohedra, which makes it easy to mistake for pyrite until the colour is compared directly.

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 an ore of

  • Cobalt — element · a cobalt ore, though most cobalt now arrives as a by-product of copper and nickel mining Wikidata

is an input to

  • Roasting — process · roasted with care — the arsenic is what gave cobalt its reputation and its name

is a component of

  • Epithermal vein — deposit type · in the deeper and hotter veins, with the nickel and arsenic minerals it usually accompanies

contains

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Crystallography Open Database
    COD Advisory Board / Vilnius University · CC0 — contributors place data in the public domain

Questions this page answers

Where it comes from, and what it becomes

Follow Cobaltite 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.

Downstream — what it becomes

  • Cobaltite → is an ore of (a cobalt ore, though most cobalt now arrives as a by-product of copper and nickel mining) → Cobalt → is a component of (a substantial addition, and one of the reasons aviation and battery demand compete for the same metal) → Nickel superalloy → is associated with (the jet engine created the industry, because no existing material survived the turbine inlet) → The wartime materials programmes complete chain
  • Cobaltite → is an input to (roasted with care — the arsenic is what gave cobalt its reputation and its name) → Roasting → produces (as the oxide, which is then reduced — roasting is the step that makes zinc sulfide smeltable) → Zinc → is an input to (the addition that makes brass; it boils below copper's melting point, which is the difficulty) → Alloying and melting → produces (zinc dissolved into molten copper, under conditions that stop the zinc boiling off) → Brass → is used as (in air rather than seawater — brass dezincifies in chloride) → Corrosion protection
  • Cobaltite → is a component of (in the deeper and hotter veins, with the nickel and arsenic minerals it usually accompanies) → Epithermal vein
  • Cobaltite → is an ore of (a cobalt ore, though most cobalt now arrives as a by-product of copper and nickel mining) → Cobalt → is a component of (the balance, and both the reason it works hot and the reason it is expensive) → Samarium–cobalt magnet → is used as (weaker and untroubled by heat, which keeps it where temperature rather than strength is the constraint) → Permanent magnets
  • Cobaltite → is an ore of (a cobalt ore, though most cobalt now arrives as a by-product of copper and nickel mining) → Cobalt → is used as (stabilises the cathode structure) → Battery electrodes
  • Cobaltite → is an ore of (a cobalt ore, though most cobalt now arrives as a by-product of copper and nickel mining) → Cobalt → is used as (cobalt blue, in use for three thousand years) → Pigment

These are the most distinct paths onward. Cobaltite ends up in others besides.