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: cubic. 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: Cubic
Crystal habit: Anhedral Grains, Inclusions
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Ultramafic Igneous Rocks

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, 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.

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.