Hloušekite is a rare nickel-cobalt arsenide mineral found in association with uraninite-bearing hydrothermal veins. It typically presents as microscopic grains or small aggregates and is primarily identified via chemical analysis in a laboratory setting due to its similarity to other nickel-cobalt minerals.

Hardness

5.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareGersdorffite Group family

Hloušekite

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

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Is this hloušekite?

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 hloušekite with a known reference. Hloušekite 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. Hloušekite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Hloušekite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: white, gray, pale yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral grains, aggregates.

Often confused with

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

mineral

Gersdorffite

Mohs 5.5

How to tell apart: Streak differs — Hloušekite leaves black, Gersdorffite leaves grayish-black.

How to tell apart: Streak differs — Hloušekite leaves black, Cobaltite leaves greyish-black.

Often found alongside hloušekite

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

All properties

Chemical formula: (Ni,Co)As₂
Mohs hardness: 5.5
Density: 6.0-6.1 g/cm³
Colors: White Gray Pale Yellow
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Anhedral Grains, Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per thumbnail specimen depending on rarity

Where rockhounds find hloušekite

Classic worldwide localities

Jáchymov, Czech Republic

Field-hunting tip

Look in hydrothermal veins country — that is the host setting where hloušekite typically forms. If you start seeing uraninite, arsenopyrite, nickelskutterudite in float, you are in the right ground. Field specimens usually show a anhedral grains, aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hloušekite?+

Mohs hardness is 5.5. It typically shows a metallic luster. The streak is black. Common colors include white, gray, pale yellow.

Where is hloušekite found?+

Notable localities include Jáchymov, Czech Republic.

How much is hloušekite worth?+

Typical asking prices fall in the range of $50-300 per thumbnail specimen depending on rarity. Quality, size, and provenance can move individual specimens well outside that range.

Is hloušekite safe to handle?+

It contains toxic constituents. Contains arsenic and nickel; avoid ingestion, inhalation of dust, and handle with gloves. Wash hands thoroughly after handling specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like hloušekite?+

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

What minerals are found with hloušekite?+

Hloušekite commonly co-occurs with Uraninite, Arsenopyrite, Nickelskutterudite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hloušekite form in?+

Hloušekite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is hloušekite used for?+

Hloušekite is used in collector.

Find hloušekite on the map

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