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Material World
Mineral · UO2

Uraninite

Uranium dioxide — the principal uranium ore, the mineral the Curies worked, and the rock in which radium and polonium were found.

Ore

Uraninite is uranium dioxide, and under its older name pitchblende it is the most consequential mineral in the history of physics. It was the residue of pitchblende that Marie and Pierre Curie processed by the tonne, and from which they separated first polonium and then radium.

It is also where the elements of the uranium decay chain are found, because it makes them: radium, radon and polonium all exist in an ore body only because uranium is steadily producing them there.

How to identify it

Uraninite is black to brownish black with a pitchy, greasy lustre, and it is extremely heavy — comparable to galena and among the densest common minerals. It is strongly radioactive, which is the definitive test and the reason specimens are handled and stored carefully.

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

  • Uranium — element · the principal uranium ore, and the pitchblende the Curies worked Wikidata

is a source for

  • Radium — element · produced continuously within the ore by uranium decay, and separated from pitchblende residues
  • Polonium — element · the other element the Curies separated from pitchblende

is a component of

  • Granite — rock · in some granites, and the reason granite terrain produces radon — uranium decays to it and the gas escapes through the fractures
  • Pegmatite — rock · in the rare-element bodies, alongside the niobium and rare earth minerals that share its incompatibility

is an input to

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 Uraninite 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

  • Uraninite → is an input to (leached with acid or alkali depending on the host rock, which is what decides the flowsheet of a uranium mill) → Solvent extraction and electrowinning → produces (roughly a fifth of world production, plated straight from solution at cathode purity without ever being melted) → Copper → is a component of → Bronze → is used to make (cast in a two-piece mould with a core, which is what bronze does better than the copper it replaced) → Bronze socketed axe → is associated with → Bronze Age complete chain
  • Uraninite → is a component of (in some granites, and the reason granite terrain produces radon — uranium decays to it and the gas escapes through the fractures) → Granite → is a source for (quarried in blocks for cladding, kerbs and monuments) → Dimension stone → is used in (quarried rather than mined, and the distinction is legal and technical rather than merely a word) → Mining and quarrying → is associated with (steam pumping allowed mines below the water table, which is what made deep coal possible) → Industrial Revolution complete chain
  • Uraninite → is an ore of (the principal uranium ore, and the pitchblende the Curies worked) → Uranium → is a source for (formed from uranium-238 in a reactor and recovered from spent fuel) → Plutonium → is a source for → Curium → is a source for → Californium
  • Uraninite → is a source for (produced continuously within the ore by uranium decay, and separated from pitchblende residues) → Radium
  • Uraninite → is a source for (the other element the Curies separated from pitchblende) → Polonium
  • Uraninite → is a component of (in the rare-element bodies, alongside the niobium and rare earth minerals that share its incompatibility) → Pegmatite

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