Stilleite is a rare zinc selenide mineral that typically occurs as massive or granular inclusions within sulfide ores. It is primarily identified by its metallic luster and dark gray color in settings where other selenide minerals are present.
Is this stilleite?
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 stilleite with a known reference. Stilleite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Stilleite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Stilleite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: dark gray, blackish gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, granular.
Often confused with
Stilleite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Stilleite leaves black, Sphalerite leaves white to yellow-brown; luster reads metallic on Stilleite and resinous to submetallic on Sphalerite.
How to tell apart: Stilleite is noticeably harder (Mohs 4.5 vs. 2.5-3); streak differs — Stilleite leaves black, Clausthalite leaves gray-black.
How to tell apart: Stilleite is noticeably harder (Mohs 4.5 vs. 2.5).
Often found alongside stilleite
Minerals reported to co-occur with stilleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ZnSe
- Mohs hardness
- 4.5
- Density
- 5.65 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins, Sedimentary Rocks Associated with Selenide Deposits
- Typical price
- $50-300 per small specimen
Where rockhounds find stilleite
Classic worldwide localities
- Shinkolobwe, Democratic Republic of the Congo
- Tilkerode, Harz Mountains, Germany
- Kidd Creek Mine, Ontario, Canada
- Qinglong, Guizhou, China
Field-hunting tip
Look in hydrothermal veins, sedimentary rocks associated with selenide deposits country — that is the host setting where stilleite typically forms. If you start seeing clausthalite, tiemannite, galena in float, you are in the right ground. Field specimens usually show a massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find stilleite on the map
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