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Material World
Mineral variety · Al2O3

Ruby

The red variety of corundum, coloured by chromium.

Gemstone

Ruby is corundum coloured red by chromium substituting for a small fraction of the aluminium. Red corundum is ruby; corundum of any other colour is sapphire. That the dividing line between the two most famous coloured gemstones is a naming convention rather than a mineralogical one is a good illustration of why the model separates what a thing is from what it is called.

Medium confidence Weak evidence 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 a variety of

is commonly confused with

  • Sapphire — mineral variety · the same mineral; only red corundum is ruby

contains

  • Aluminium — element · ruby is corundum; the chromium that colours it is a trace substituent, not a major component Wikidata
  • Oxygen — element Wikidata

is a component of

  • Marble — rock · an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them

is used as

  • Jewellery and adornment — application · corundum coloured by chromium, and hard enough at 9 to be worn daily for a lifetime without visible wear

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)

Questions this page answers

Where it comes from, and what it becomes

Follow Ruby 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

  • Ruby → is a component of (an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them) → Marble → is an input to (the dimension stone trade's premium material, and the reason Carrara has been worked continuously for two thousand years) → Quarrying → produces (cut rather than blasted, because a quarry that shatters its stone has destroyed what it came for) → 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
  • Ruby → is used as (corundum coloured by chromium, and hard enough at 9 to be worn daily for a lifetime without visible wear) → Jewellery and adornment
  • Ruby → is a component of (an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them) → Marble → is a source for (quarried where a stone that takes a polish is wanted) → 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
  • Ruby → is a component of (an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them) → Marble → is produced at (quarried since Roman times) → Carrara
  • Ruby → is a component of (an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them) → Marble → is an input to (the dimension stone trade's premium material, and the reason Carrara has been worked continuously for two thousand years) → Quarrying → produces (crushed and graded from quarried rock, and the grading is the product — a concrete mix specifies a size distribution, not a stone) → Aggregate → is a component of (95 per cent of it by mass — the stone carries the load and the bitumen keeps the water out) → Asphalt concrete → is used as (as pavement rather than as structure: a surface that spreads a wheel load into the ground beneath it) → Structural engineering
  • Ruby → is a component of (an accessory mineral rather than a rock-forming one: ruby grows in metamorphosed limestone where the rock was alumina-rich and unusually poor in silica, which is the classic Burmese occurrence and the reason marble hosts the best of them) → Marble → is a source for (quarried where a stone that takes a polish is wanted) → Dimension stone → is used in (cladding, flooring, kerbs and monuments) → Construction

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