Cadmoselite is an extremely rare cadmium selenide mineral that typically occurs as microscopic black grains or inclusions within larger ore minerals. It is primarily found in complex hydrothermal settings alongside other selenides and uranium minerals. Due to its scarcity and metallic appearance, it is highly sought after by advanced mineral collectors specializing in rare species.
Is this cadmoselite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch cadmoselite with a known reference. Cadmoselite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to adamantine.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: fine-grained massive or as minute inclusions.
Often confused with
Cadmoselite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cadmoselite leaves black, Greenockite leaves yellow-orange to brick-red; luster reads resinous to adamantine on Cadmoselite and adamantine to resinous on Greenockite.
How to tell apart: Streak differs, so Cadmoselite leaves black, Sphalerite leaves pale brown to pale yellow and white.
Often found alongside cadmoselite
Minerals reported to co-occur with cadmoselite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CdSe
- Mohs hardness
- 4
- Density
- 5.47 g/cm³
- Colors
- Streak
- Black
- Luster
- Resinous to adamantine
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Fine-grained massive or as minute inclusions
- Cleavage
- Perfect, apparently prismatic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In sedimentary strata, under reducing secondary conditions of medium to high alkalinity (Ust’Uyuk deposit, Russia)
Where rockhounds find cadmoselite
Classic worldwide localities
- Ust’Uyuk V–Se–U deposit, Tuva, Russia
- Tuminico, Sierra de Cacho, La Rioja Province, Argentina
Field-hunting tip
Where it forms: In sedimentary strata, under reducing secondary conditions of medium to high alkalinity (Ust’Uyuk deposit, Russia). If you start seeing ferroselite, clausthalite, cadmian sphalerite in float, you are in the right ground. Typical habit: fine-grained massive or as minute inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cadmoselite?+
Where is cadmoselite found?+
Is cadmoselite safe to handle?+
What rocks look like cadmoselite?+
What minerals are found with cadmoselite?+
What kind of rock does cadmoselite form in?+
What is cadmoselite used for?+
Find cadmoselite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
