Iridium (Ir, element 77) is never mined on its own anywhere on Earth; every gram reaches the market as a co-product of platinum and palladium ore, chiefly from one South African orebody. That fact separates iridium's supply story from platinum's, and explains why iridium has no mine plan, no dedicated miner and no country-level reserve figure of its own. This page traces iridium from the crustal process that concentrates it, through the ore and minerals that carry it, to why no agency publishes an iridium-only reserve tonnage.
Where Is Iridium Found?#
Iridium (Ir, element 77) occurs almost exclusively within platinum-group-element ore bodies and is never mined as a primary product; every commercial tonne is recovered as a co-product of platinum and palladium mining. It is one of the six platinum group metals (PGMs), and virtually all of it comes from the UG2 Chromitite of South Africa's Bushveld Complex, where it runs alongside five other platinum-group metals in the same rock. No producer books an iridium mine plan, because no orebody is worked for iridium alone; the full iridium (Ir), element 77 profile, beyond where it is found, covers its properties and uses.
Why PGMs Concentrate Where They Do#
Platinum-group metals concentrate in ore at roughly 10,000 times their abundance in the Earth's upper continental crust, an enrichment factor few mined commodities approach. Upper continental crust averages just 0.0005 ppm platinum, against 5 to 15 ppm total PGE in ore actually mined, per the USGS Platinum-Group Elements study (USGS Professional Paper 1802-N, 2017). That gap opens only when magnesium-rich magma, formed by a high degree of partial melting, carries the crust's scarce budget upward and reaches sulphur saturation, exsolving an immiscible sulphide liquid; the larger the magma volume equilibrating with a given pocket of that sulphide, the more metal concentrates into it, a relationship geologists call the R-factor. Iridium rides this process but partitions differently from platinum once the liquid crystallizes, covered next.
The Deposit Type That Supplies Iridium#
Iridium's supply comes from a single deposit type: chromitite reefs within magmatic layered intrusions, specifically the UG2 Chromitite of the Bushveld Complex. Economic geologists recognize five broad classes of platinum-group-element occurrence, but essentially all mined output comes from the magmatic class (USGS PP 1802-N):
- Magmatic (reef-type, contact-type, conduit-type): source of virtually all mined PGE, including every commercial gram of iridium.
- Ophiolite chromitite: geologically the richest iridium-relative-to-platinum environment on Earth, but never economically mined (see the unique beat below).
- Placer: supplied almost all world PGE output before 1920, dominated by platinum, with little iridium.
- Residual (laterite): PGE-enriched at a few sites worldwide, never a commercial iridium source.
- Hydrothermal and sedimentary: PGE-bearing occurrences exist but are sub-economic everywhere studied.
Within the magmatic class, iridium comes specifically from reef-type intrusions rather than the conduit-type or contact-type sub-types that dominate palladium supply elsewhere.
| Magmatic sub-type | Geometry | Sulphide content | Type examples | Iridium relevance |
|---|---|---|---|---|
| Reef-type | Thin, laterally continuous horizon, centimeters to meters thick | Low, usually under a few volume percent | Merensky Reef, UG2 Chromitite (Bushveld); Main Sulphide Zone (Great Dyke) | UG2 Chromitite is iridium's primary and essentially only commercial source |
| Contact-type | Thick, strata-bound zone at an intrusion's base | Typically 3 to 5 volume percent | Platreef (Bushveld northern limb); Duluth Complex | Palladium-dominant; carries little iridium |
| Conduit-type | Elongate sills and dykes feeding flood basalts | High, massive sulphide bodies | Noril'sk-Talnakh, Russia | Palladium-dominant by-product stream; iridium content is minor |
At high temperature, iridium behaves as one of the "IPGE" elements (iridium, osmium, ruthenium), partitioning into the early-crystallizing monosulphide solid solution rather than the residual copper-rich liquid that platinum and palladium favor (USGS PP 1802-N). Chromite crystallizes early too, tying iridium mineralogically to chromite, exactly why chromite-rich UG2 carries far more iridium than the chromite-poor Merensky Reef beside it.
Iridium-Bearing Minerals#
Iridium's principal carrier is native iridium, a natural alloy with osmium and ruthenium, alongside iridium held in solid solution within other sulphide and arsenide minerals rather than as a discrete iridium compound. The Handbook of Mineralogy lists more than 100 platinum-group minerals overall, but only a handful carry meaningful iridium.
| Mineral | Formula | Hardness (Mohs) | Density (g/cm3) | Occurrence |
|---|---|---|---|---|
| Native iridium | (Ir,Os,Ru) | 6 to 7 | 22.66 | Among the densest natural substances; forms in chromitites and their derived placers |
| Irarsite | (Ir,Ru,Rh,Pt)AsS | Not scratched by a steel needle | 11.92 | Grains to 1 mm, intergrown with hollingworthite or laurite; type locality the Onverwacht mine, South Africa |
| Laurite-erlichmanite series | RuS2 to OsS2 | 7.5 | 6.39 to 9.59 | Iridium substitutes into this ruthenium-osmium sulphide series; laurite is characteristically associated with chromite |
Iridium also enters pyrrhotite (Fe(1-x)S) in solid solution alongside osmium, ruthenium and rhodium, a base-metal sulphide host that forms no discrete mineral of its own (USGS PP 1802-N). Native iridium's density of 22.66 g/cm3 sits a fraction above native osmium's 22.59 g/cm3, the two densest metals in nature, per the Handbook of Mineralogy.
The Other Iridium Environment#
Ophiolite chromitites worldwide carry more iridium relative to platinum than any Bushveld or Noril'sk ore, yet none has ever produced a commercial ounce. Podiform chromitites in ophiolite belts are consistently iridium-enriched, the mirror image of the platinum- and palladium-dominant assemblage at Bushveld and Noril'sk, with a PGM suite of laurite, erlichmanite and osmium-iridium-ruthenium alloys rather than Bushveld's sperrylite and cooperite (USGS PP 1802-N). A few even carry platinum enrichment, but the USGS states plainly that these occurrences "are too small to be of any economic consequence." The rock type most enriched in iridium relative to platinum has therefore never been mined for either, and every commercial tonne still traces back to UG2 Chromitite.
Where Iridium Reserves Are Concentrated#
No producer or agency publishes an iridium-specific reserve tonnage, because iridium is never assayed or sold as its own line item; it moves inside a combined platinum-group-metal basket. Rhodium, ruthenium and iridium always report as a share of a 4E (platinum, palladium, rhodium, gold) or 6E (adding ruthenium and iridium) figure, so USGS Mineral Commodity Summaries 2026 gives one PGM reserve figure of more than 76,000,000 kg, of which South Africa holds 63,000,000 kg (82.9 percent), without breaking iridium out.
| Operation | Orebody | Iridium, % of 6E |
|---|---|---|
| Impala Rustenburg | UG2 Chromitite | 3.4% |
| Impala Bafokeng | UG2 Chromitite | 3.6% |
| Afplats (Leeuwkop) | UG2 Chromitite | 3.7% |
| Impala Rustenburg | Merensky Reef | 2.0% |
| Impala Bafokeng | Merensky Reef | 1.4% |
| Zimplats and Mimosa | Great Dyke Main Sulphide Zone | 1.8% to 2.0% |
Iridium runs 2.6 to 3.7 percent of 6E in UG2 Chromitite against 0.8 to 2.0 percent in the Merensky Reef, calculated from Impala Platinum's 2025 contained-ounce disclosures (Implats, Mineral Resource and Mineral Reserve Statement 2025). South Africa's UG2 Chromitite supplies the large majority of world iridium output, and this split is the closest thing to a reserve figure iridium has.
From Ore to Market: Where This Page Stops#
Iridium's occurrence story ends at the ore body and the mineral grain; mining, refining and sale belong to other pages. Once UG2 Chromitite is refined, the metal moves into pricing, investment and market-supply questions covered on the iridium price today and iridium market pages, and into recycling and scrap economics this page does not address.
Occurrence of the Other PGMs#
All six platinum-group metals share the same handful of ore bodies, in sharply different proportions from one metal to the next.
| Metal | Primary source | Status |
|---|---|---|
| Platinum occurrence | Bushveld Complex and Great Dyke | Mined as a primary product |
| Palladium occurrence | Bushveld Platreef and Noril'sk-Talnakh | Primary product in South Africa; byproduct of nickel mining in Russia |
| Rhodium occurrence | UG2 Chromitite, Bushveld Complex | Never mined on its own; co-product |
| Iridium occurrence (this page) | UG2 Chromitite, Bushveld Complex | Never mined on its own; co-product |
| Ruthenium occurrence | UG2 Chromitite, Bushveld Complex | Never mined on its own; co-product |
| Osmium occurrence | Recovered from PGM refinery streams | Never mined on its own; not separately reported by any producer |
Related Iridium Facts#
Iridium's occurrence connects directly to its physical and chemical identity, covered on the metal's other attribute pages:
- Iridium properties: the density and hardness that follow from its native-metal and sulpharsenide mineral forms.
- Iridium uses: how metal recovered from UG2 Chromitite reaches spark plugs, crucibles and electrolyzer catalysts.
- Iridium alloys: how iridium's natural alloying with osmium and ruthenium in the ore relates to engineered alloys.
Frequently Asked Questions#
Where can you find iridium naturally? Iridium occurs naturally in UG2 Chromitite, the chromite-rich reef of South Africa's Bushveld Complex, as native iridium and as a trace component of sulpharsenide minerals; no deposit is mined for iridium alone.
Is iridium rarer than gold? Iridium is one of the rarest elements in the Earth's crust; see how rare iridium is for the specific comparison against gold.
How much is 1 gram of iridium worth? Iridium's value tracks the dealer-quoted market rather than a public exchange price; current values are on the iridium price today page, not restated here.
Where is the most iridium found? The UG2 Chromitite of South Africa's Bushveld Complex is the world's dominant iridium source, carrying 2.6 to 3.7 percent of its combined platinum-group-metal content as iridium, well above the Merensky Reef mined in the same complex.
How much is 1 lb of iridium worth? As with the per-gram figure, iridium's per-pound value tracks live dealer quotes; see the iridium price page for current values.
How rare is iridium on Earth? Iridium is among the scarcest metals in the crust and is recovered only as a minor co-product of platinum-group-metal mining, never as a primary target; the rarity page linked above covers the abundance figures.