Wurtzite is a hexagonal polymorph of zinc sulfide, often found in low-temperature hydrothermal veins. It typically displays brownish, resinous pyramidal crystals or fibrous crusts that can be easily mistaken for its common cousin, sphalerite.
Is this wurtzite?
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 wurtzite with a known reference. Wurtzite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous, brilliant submetallic on crystal faces.
- 4Match the color rangeCompare against the expected color range: brownish black, orange brown, reddish brown, black.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: colloform, radial, tabular.
Often confused with
Wurtzite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Wurtzite leaves brown, Sphalerite leaves pale brown to pale yellow and white.
How to tell apart: Streak differs, so Wurtzite leaves brown, Greenockite leaves yellow-orange to brick-red; luster reads resinous, brilliant submetallic on crystal faces on Wurtzite and adamantine to resinous on Greenockite.
Often found alongside wurtzite
Minerals reported to co-occur with wurtzite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ZnS
- Mohs hardness
- 3.5-4
- Density
- 4.09 g/cm³
- Streak
- Brown
- Luster
- Resinous, brilliant submetallic on crystal faces
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Colloform, radial, tabular
- Cleavage
- Easy on {1120}; difficult on {0001}
- Fluorescence
- Orange red under LW UV
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- Of hydrothermal origin in veins with other sulfides
Where rockhounds find wurtzite
1 mapped spotsClassic worldwide localities
- Thomaston Dam, Litchfield Co., Connecticut, USA
- Leonard mine, Butte, Silver Bow Co., Montana, USA
- Frisco, Beaver Co., Utah, USA
- Joplin district, Jasper Co., Missouri, USA
- Rachelshausen, near Gladenbach, Hesse, Germany
- Liskeard, Cornwall, England
Field-hunting tip
Where it forms: Of hydrothermal origin in veins with other sulfides. If you start seeing sphalerite, pyrite, chalcopyrite in float, you are in the right ground. Typical habit: colloform, radial, tabular. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Pennsylvania. Start trip planning there.
Common questions
How do you identify wurtzite?+
Where is wurtzite found?+
Can I find wurtzite in the United States?+
What rocks look like wurtzite?+
What minerals are found with wurtzite?+
What kind of rock does wurtzite form in?+
What is wurtzite used for?+
Find wurtzite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
