Isoferroplatinum is a rare platinum-iron alloy typically occurring as small metallic grains within mafic and ultramafic igneous complexes. It is distinguished from native platinum by its high iron content and distinct optical properties under reflected light, often requiring microprobe analysis for positive identification.
Is this isoferroplatinum?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch isoferroplatinum with a known reference. Isoferroplatinum sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Isoferroplatinum leaves a grayish-black streak.
- 3Read the lusterHold the specimen under a strong light. Isoferroplatinum typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, light steel-gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains, nuggets, rounded inclusions in chromite.
Often confused with
Isoferroplatinum vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Isoferroplatinum leaves grayish-black, Platinum Nuggets leaves silvery-white.
How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 4.5); streak differs — Isoferroplatinum leaves grayish-black, Sperrylite leaves black.
Often found alongside isoferroplatinum
Minerals reported to co-occur with isoferroplatinum. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pt₃Fe
- Mohs hardness
- 4.5
- Density
- 17.4-18.3 g/cm³
- Streak
- Grayish-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral Grains, Nuggets, Rounded Inclusions in Chromite
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Reference
- Host rock
- Ultramafic Igneous Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find isoferroplatinum
Classic worldwide localities
- Stillwater Complex, USA
- Bushveld Complex, South Africa
- Ural Mountains, Russia
- Tulameen Complex, Canada
Field-hunting tip
Look in ultramafic igneous rocks country — that is the host setting where isoferroplatinum typically forms. If you start seeing chromite, olivine, pyroxene in float, you are in the right ground. Field specimens usually show a anhedral grains, nuggets, rounded inclusions in chromite habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find isoferroplatinum on the map
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