Petříčekite is a rare copper selenide mineral typically found in hydrothermal vein deposits. It is often identified by its metallic luster and association with other selenide species in rare-mineral localities.

Hardness

5-6

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareLöllingite Group family

Petříčekite

Hardness: 5-6
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this petříčekite?

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 petříčekite with a known reference. Petříčekite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Petříčekite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Petříčekite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: silver-white, tin-white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals.

Often confused with

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

mineral

Löllingite

Mohs 5.5-6

How to tell apart: Streak differs, so Petříčekite leaves black, Löllingite leaves gray-black.

How to tell apart: Streak differs, so Petříčekite leaves black, Marcasite leaves greyish-black.

Compare →

Often found alongside petříčekite

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

All properties

Chemical formula: CuSe₂
Mohs hardness: 5-6
Density: 7.5-7.7 g/cm³
Colors: Silver-white Tin-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Prismatic Crystals
Cleavage: Distinct
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Selenide Veins
Typical price: $50-300 per specimen

Where rockhounds find petříčekite

Classic worldwide localities

Petříček, Czech Republic
Markossa, Sweden

Field-hunting tip

Look in hydrothermal selenide veins country, the host setting where petříčekite typically forms. If you start seeing clausthalite, umangite, berzelianite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify petříčekite?+

Mohs hardness is 5-6. It typically shows a metallic luster. The streak is black. Common colors include silver-white, tin-white.

Where is petříčekite found?+

Notable localities include Petříček, Czech Republic; Markossa, Sweden.

How much is petříčekite worth?+

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

Is petříčekite safe to handle?+

It contains toxic constituents. Contains selenium, which is toxic if ingested or inhaled as dust. Handle with care and wash hands after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like petříčekite?+

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

What minerals are found with petříčekite?+

Petříčekite commonly co-occurs with Clausthalite, Umangite, Berzelianite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does petříčekite form in?+

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

What is petříčekite used for?+

Petříčekite is used in collector.

Find petříčekite on the map

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