Greenockite is a rare cadmium sulfide mineral that frequently appears as bright yellow or orange crusts and coatings on other minerals like sphalerite. It is prized by collectors for its vivid color and strong fluorescence, but it should be handled with extreme care due to its toxic cadmium content.
Is this greenockite?
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 greenockite with a known reference. Greenockite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Greenockite leaves a brick-red to orange-yellow streak.
- 3Read the lusterHold the specimen under a strong light. Greenockite typically shows a adamantine to resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange, brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: pyramidal crystals, crusts, coatings.
Often confused with
Greenockite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Greenockite leaves brick-red to orange-yellow, Sphalerite leaves white to yellow-brown; luster reads adamantine to resinous on Greenockite and resinous to submetallic on Sphalerite.
How to tell apart: Streak differs — Greenockite leaves brick-red to orange-yellow, Wurtzite leaves brownish-yellow to light brown; luster reads adamantine to resinous on Greenockite and resinous on Wurtzite.
How to tell apart: Greenockite is noticeably harder (Mohs 3-3.5 vs. 1.5-2); streak differs — Greenockite leaves brick-red to orange-yellow, Orpiment leaves yellow; luster reads adamantine to resinous on Greenockite and resinous on Orpiment.
Often found alongside greenockite
Minerals reported to co-occur with greenockite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CdS
- Mohs hardness
- 3-3.5
- Density
- 4.8 g/cm³
- Streak
- Brick-red to Orange-yellow
- Luster
- Adamantine to Resinous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Pyramidal Crystals, Crusts, Coatings
- Cleavage
- Perfect Prismatic
- Fluorescence
- Bright Yellow-orange Under UV
- Rarity
- Rare
- Uses
- Collector, Ore of Cadmium
- Host rock
- Hydrothermal Veins, Volcanic Cavities
- Typical price
- $20-150 thumbnail, $200-800 cabinet
Where rockhounds find greenockite
2 mapped spotsClassic worldwide localities
- Bishopton, Scotland
- Friedensville, Pennsylvania, USA
- Llallagua, Bolivia
- Tsumeb, Namibia
Field-hunting tip
Look in hydrothermal veins, volcanic cavities country — that is the host setting where greenockite typically forms. If you start seeing sphalerite, smithsonite, prehnite in float, you are in the right ground. Field specimens usually show a pyramidal crystals, crusts, coatings habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arkansas, Missouri — start trip planning there.
Common questions
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Find greenockite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
