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

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 — 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 — that is 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.