Černýite is a rare copper cadmium tin sulfide found primarily in granitic pegmatites. It typically appears as an opaque, black massive mineral and is nearly impossible to distinguish from other stannite-group minerals without chemical analysis like EDS or XRD.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareStannite Group family

Černýite

Hardness: 3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

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Is this černýite?

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 černýite with a known reference. Černýite 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. Černýite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Černýite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black, grayish-black.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: massive, granular, inclusions.

Often confused with

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

How to tell apart: Streak differs, so Černýite leaves black, Sphalerite leaves white to yellow-brown; luster reads metallic on Černýite and resinous to submetallic on Sphalerite.

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Often found alongside černýite

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

All properties

Chemical formula: Cu₂CdSnS₄
Mohs hardness: 3.5
Density: 4.92 g/cm³
Colors: Black Grayish-black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Massive, Granular, Inclusions
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find černýite

Classic worldwide localities

Hugo Mine, South Dakota, USA
Stannum, New South Wales, Australia

Field-hunting tip

Look in granite pegmatites country, the host setting where černýite typically forms. If you start seeing sphalerite, chalcopyrite, galena in float, you are in the right ground. Field specimens usually show a massive, granular, inclusions habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify černýite?+

Mohs hardness is 3.5. It typically shows a metallic luster. The streak is black. Common colors include black, grayish-black.

Where is černýite found?+

Notable localities include Hugo Mine, South Dakota, USA; Stannum, New South Wales, Australia.

How much is černýite 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 černýite safe to handle?+

It contains toxic constituents. Contains cadmium, a toxic heavy metal. Wash hands thoroughly after handling and do not inhale dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like černýite?+

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

What minerals are found with černýite?+

Černýite commonly co-occurs with Sphalerite, Chalcopyrite, Galena, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does černýite form in?+

Černýite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is černýite used for?+

Černýite is used in collector, scientific research.

Find černýite on the map

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