Isomertieite is a rare palladium antimony arsenide mineral typically found as microscopic inclusions within platinum-group element deposits. It is most often identified through reflected light microscopy or microprobe analysis in polished sections from ultramafic complexes. It is a highly sought-after species for specialist mineral collectors of platinum group minerals.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Isomertieite

Hardness: 3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this isomertieite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch isomertieite with a known reference. Isomertieite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Isomertieite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Isomertieite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: white, light yellow, silver-white.
5
Look at form & habit
Crystal system: trigonal. Typical habit: anhedral grains, inclusions.

Often confused with

Isomertieite vs. its common look-alikes — and how to tell them apart in the field.

Often found alongside isomertieite

Minerals reported to co-occur with isomertieite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Pd₁₁Sb₂As₂
Mohs hardness: 3.5
Density: 9.94 g/cm³
Colors: White Light Yellow Silver-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Anhedral Grains, Inclusions
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Ultramafic Igneous Rocks
Typical price: $100-500 per specimen

Where rockhounds find isomertieite

Classic worldwide localities

Stillwater Complex, USA
Bushveld Complex, South Africa
Kondyor Massif, Russia

Field-hunting tip

Look in ultramafic igneous rocks country — that is the host setting where isomertieite typically forms. If you start seeing sperrylite, palladium, chalcopyrite in float, you are in the right ground. Field specimens usually show a anhedral grains, inclusions habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify isomertieite?+

Mohs hardness is 3.5. It typically shows a metallic luster. The streak is black. Common colors include white, light yellow, silver-white.

Where is isomertieite found?+

Notable localities include Stillwater Complex, USA; Bushveld Complex, South Africa; Kondyor Massif, Russia.

How much is isomertieite worth?+

Typical asking prices fall in the range of $100-500 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is isomertieite safe to handle?+

It contains toxic constituents. Contains arsenic and palladium; avoid inhaling dust during processing and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like isomertieite?+

Isomertieite is most often confused with Mertieite, Stibiopalladinite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with isomertieite?+

Isomertieite commonly co-occurs with Sperrylite, Palladium, Chalcopyrite, Pentlandite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does isomertieite form in?+

Isomertieite typically forms in ultramafic igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is isomertieite used for?+

Isomertieite is used in collector.

Find isomertieite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.