Zemannite is a rare tellurite mineral typically found as small, dark brown prismatic to acicular crystals. It is primarily known from oxidized zones of tellurium-rich ore deposits, often appearing as coatings or drusy aggregates on rock surfaces.
Is this zemannite?
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 zemannite with a known reference. Zemannite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: dark brown, light brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular, hexagonal, prismatic.
Often confused with
Zemannite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Zemannite leaves white, Cesbronite leaves pale green; luster reads adamantine on Zemannite and subadamantine on Cesbronite.
How to tell apart: Emmonsite is the harder of the two (Mohs ~5 vs. 3); streak differs, so Zemannite leaves white, Emmonsite leaves pale yellow; luster reads adamantine on Zemannite and vitreous on Emmonsite.
Often found alongside zemannite
Minerals reported to co-occur with zemannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₀.₅ZnFe³⁺(TeO₃)₃·4.5H₂O
- Mohs hardness
- 3
- Density
- 4.05 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Translucent to transparent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular, hexagonal, prismatic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of a hydrothermal Au–Te deposit
Where rockhounds find zemannite
Classic worldwide localities
- Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of a hydrothermal Au–Te deposit. If you start seeing tellurium, tellurite, paratellurite in float, you are in the right ground. Typical habit: acicular, hexagonal, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zemannite?+
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Find zemannite on the map
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