Place

Bushveld Igneous Complex

One geological intrusion holds most of the world's platinum, and there is no comparable second.

A layered igneous intrusion in South Africa, around two billion years old and among the largest known. Magma cooled slowly enough for minerals to crystallise and settle into distinct layers, and two of those layers — the Merensky Reef and the UG2 chromitite — carry platinum-group elements in concentrations found essentially nowhere else.

The layering is the point. Ordinary crustal rock contains platinum at a few parts per billion; the reefs concentrate it enough to mine, and they do so in seams that can be followed for tens of kilometres and are often less than a metre thick.

History

Described geologically in the nineteenth century; platinum discovered in the Merensky Reef by Hans Merensky in 1924. Mining has followed the reefs ever since, to depths beyond two kilometres.

Economic significance

It is the clearest case of geological concentration as a supply constraint. Most of the world's platinum and a large share of its rhodium come from one intrusion in one country, and no comparable alternative deposit is known — so the supply is exposed to the electricity, labour relations and depth economics of a single mining district.

Rhodium's price history is the visible consequence: a metal used in milligram quantities in catalytic converters, from a source that cannot be expanded quickly, has moved by an order of magnitude within a year more than once.

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.

produces

Platinum — element · from the Merensky Reef and the UG2 chromitite, in seams often under a metre thick and followed for tens of kilometres
Rhodium — element · as a co-product, and its price history is what a supply that cannot be expanded quickly looks like

is a source of

Platinum — element · concentrated by two billion years of magmatic layering into seams found essentially nowhere else

Sources

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

Where it comes from, and what it becomes

Follow Bushveld Igneous Complex 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

Bushveld Igneous Complex → produces (from the Merensky Reef and the UG2 chromitite, in seams often under a metre thick and followed for tens of kilometres) → 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
Bushveld Igneous Complex → produces (as a co-product, and its price history is what a supply that cannot be expanded quickly looks like) → Rhodium → is produced by (from the same slimes and the same platinum-group concentrate, and rarer in them than palladium by an order of magnitude) → 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
Bushveld Igneous Complex → produces (from the Merensky Reef and the UG2 chromitite, in seams often under a metre thick and followed for tens of kilometres) → 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 extracted from (the principal copper ore worldwide) → Chalcopyrite
Bushveld Igneous Complex → produces (as a co-product, and its price history is what a supply that cannot be expanded quickly looks like) → Rhodium → is produced by (from the same slimes and the same platinum-group concentrate, and rarer in them than palladium by an order of magnitude) → Electrorefining → takes as input (as impure smelted anodes, around 99% copper, which is not pure enough for wire) → Copper → is extracted from (the principal copper ore worldwide) → Chalcopyrite
Bushveld Igneous Complex → produces (from the Merensky Reef and the UG2 chromitite, in seams often under a metre thick and followed for tens of kilometres) → 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 (reduced with carbon to metallic tin) → Cassiterite
Bushveld Igneous Complex → produces (from the Merensky Reef and the UG2 chromitite, in seams often under a metre thick and followed for tens of kilometres) → 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 (reduced with coke in a blast furnace) → Hematite

These are the most distinct paths back. Bushveld Igneous Complex can be traced through others besides.