Hongshiite is a rare platinum-copper alloy typically found as minute grains or inclusions within sulfide deposits. It is best identified through laboratory analysis such as electron microprobe or X-ray diffraction due to its microscopic habit and resemblance to other platinum-group minerals.
Is this hongshiite?
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 hongshiite with a known reference. Hongshiite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hongshiite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hongshiite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, pale yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: irregular grains, inclusions.
Often confused with
Hongshiite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Cooperite is the harder of the two (Mohs 4-5 vs. 2.5-3); streak differs — Hongshiite leaves white, Cooperite leaves black.
How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 2.5-3); streak differs — Hongshiite leaves white, Sperrylite leaves black.
How to tell apart: Platinum is the harder of the two (Mohs 4-4.5 vs. 2.5-3); streak differs — Hongshiite leaves white, Platinum leaves steel-gray.
Often found alongside hongshiite
Minerals reported to co-occur with hongshiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PtCu
- Mohs hardness
- 2.5-3
- Density
- 15.7-16.0 g/cm³
- Colors
- Streak
- White
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Irregular Grains, Inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Ultramafic Igneous Rocks
- Typical price
- $100-500 thumbnail
Where rockhounds find hongshiite
Classic worldwide localities
- Hongshi-la, China
- Stillwater Complex, USA
- Bushveld Complex, South Africa
Field-hunting tip
Look in ultramafic igneous rocks country — that is the host setting where hongshiite typically forms. If you start seeing platinum, palladium, chalcopyrite in float, you are in the right ground. Field specimens usually show a irregular grains, inclusions habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find hongshiite on the map
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