Polkovicite is a rare germanium-bearing sulfide mineral that typically occurs as small, brownish gray metallic grains within complex sulfide ore assemblages. It is primarily identified through specialized mineralogical analysis like microprobe testing due to its visual similarity to other dark sulfide minerals. It is famously associated with the unique germanium-rich mineralization found in the Tsumeb Mine.

Hardness

3.5-4

Mohs

Luster

Metallic

Streak

Dark Gray

Transparency

Opaque

mineralrareStannite Group family

Polkovicite

Hardness: 3.5-4
Luster: Metallic
Streak: Dark Gray
Transparency: Opaque

No image

Is this polkovicite?

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 polkovicite with a known reference. Polkovicite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Polkovicite leaves a dark gray streak.
3
Read the luster
Hold the specimen under a strong light. Polkovicite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: brownish gray.
5
Look at form & habit
Crystal system: cubic. Typical habit: granular to massive.

Often confused with

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

mineral

Stannite

Mohs 3.5

How to tell apart: Streak differs, so Polkovicite leaves dark gray, Stannite leaves blackish.

How to tell apart: Streak differs, so Polkovicite leaves dark gray, Germanite leaves black.

Often found alongside polkovicite

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

All properties

Chemical formula: (Fe,Zn)₂GeS₄
Mohs hardness: 3.5-4
Density: 4.49 g/cm³
Colors: Brownish Gray
Streak: Dark Gray
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Granular to Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Polymetallic Hydrothermal Ore Deposits

Where rockhounds find polkovicite

Classic worldwide localities

Polkovice mine, Lower Silesia, Poland

Field-hunting tip

Look in polymetallic hydrothermal ore deposits country, the host setting where polkovicite typically forms. If you start seeing germanite, renierite, tsumebite in float, you are in the right ground. Field specimens usually show a granular to massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify polkovicite?+

Mohs hardness is 3.5-4. It typically shows a metallic luster. The streak is dark gray. Common colors include brownish gray.

Where is polkovicite found?+

Notable localities include Polkovice mine, Lower Silesia, Poland.

Is polkovicite safe to handle?+

It contains toxic constituents. Contains heavy metals; wash hands thoroughly after handling and avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like polkovicite?+

Polkovicite is most often confused with Stannite, Germanite, Renierite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with polkovicite?+

Polkovicite commonly co-occurs with Germanite, Renierite, Tsumebite, Galena. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does polkovicite form in?+

Polkovicite typically forms in polymetallic hydrothermal ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is polkovicite used for?+

Polkovicite is used in collector.

Find polkovicite on the map

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