Krutovite is a rare nickel arsenide mineral that occurs primarily as metallic grains or small aggregates within hydrothermal vein systems. It is notoriously difficult to identify without chemical analysis due to its similarity to other nickel and cobalt arsenides.

Hardness

5.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Krutovite

Hardness: 5.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this krutovite?

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 krutovite with a known reference. Krutovite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: gray white.
5
Look at form & habit
Crystal system: cubic. Typical habit: grains, inclusions in other minerals.

Often confused with

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

How to tell apart: Streak differs, so Krutovite leaves black, Rammelsbergite leaves grayish black.

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Often found alongside krutovite

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

All properties

Chemical formula: NiAs₂
Mohs hardness: 5.5
Density: 7.08-7.12 g/cm³
Colors: Gray white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Grains, inclusions in other minerals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In Co–Ni–As sulfide veins of hydrothermal origin

Where rockhounds find krutovite

Classic worldwide localities

Geshiber vein, Jáchymov (Joachimsthal), Czech Republic (type locality)
Khovu-Aksy Ni–Co deposit, Tuva, Siberia, Russia

Field-hunting tip

Where it forms: In Co–Ni–As sulfide veins of hydrothermal origin. If you start seeing nickel-skutterudite, tennantite, nickeline in float, you are in the right ground. Typical habit: grains, inclusions in other minerals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify krutovite?+

Mohs hardness is 5.5. Luster: metallic. The streak is black. Common colors include gray white.

Where is krutovite found?+

Notable localities include Geshiber vein, Jáchymov (Joachimsthal), Czech Republic (type locality); Khovu-Aksy Ni–Co deposit, Tuva, Siberia, Russia.

Is krutovite safe to handle?+

Krutovite contains arsenic and nickel and calls for real care. Contains arsenic, a toxic element. Handle with care, wash hands after touching, and avoid inhaling dust.

What rocks look like krutovite?+

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

What minerals are found with krutovite?+

Krutovite commonly co-occurs with Nickel-skutterudite, Tennantite, Nickeline, Breithauptite, Löllingite, Rammelsbergite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does krutovite form in?+

Where it forms: In Co–Ni–As sulfide veins of hydrothermal origin. Working float back to the host body is the standard way to chase a fresh occurrence.

What is krutovite used for?+

Krutovite is used in collector.

Find krutovite on the map

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