Rustenburgite is an extremely rare platinum-tin intermetallic mineral typically found as microscopic inclusions within other platinum group minerals. It is primarily identified through advanced laboratory analysis like scanning electron microscopy in layered igneous intrusions. Specimens are generally limited to small grains or inclusions rather than large distinct crystals.
Is this rustenburgite?
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 rustenburgite with a known reference. Rustenburgite sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rustenburgite leaves a grey streak.
- 3Read the lusterHold the specimen under a strong light. Rustenburgite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, cream white.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains.
Often confused with
Rustenburgite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 3.5-4); streak differs — Rustenburgite leaves grey, Sperrylite leaves black.
How to tell apart: Streak differs — Rustenburgite leaves grey, Cooperite leaves black.
How to tell apart: Streak differs — Rustenburgite leaves grey, Platinum leaves steel-gray.
Often found alongside rustenburgite
Minerals reported to co-occur with rustenburgite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pt₃Sn
- Mohs hardness
- 3.5-4
- Density
- 16.1 g/cm³
- Colors
- Streak
- Grey
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Ultramafic Igneous Rocks
- Typical price
- $50-500 depending on specimen size and purity
Where rockhounds find rustenburgite
Classic worldwide localities
- Bushveld Complex, South Africa
- Stillwater Complex, USA
- Norilsk, Russia
Field-hunting tip
Look in ultramafic igneous rocks country — that is the host setting where rustenburgite typically forms. If you start seeing platinum, cooperite, braggite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rustenburgite on the map
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