Metaköttigite is a rare zinc arsenate mineral that forms as an alteration product of köttigite. Collectors typically find it as yellow-to-bluish gray powdery crusts or masses in highly oxidized portions of arsenic-rich zinc ore deposits.
Is this metaköttigite?
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 metaköttigite with a known reference. Metaköttigite sits at Mohs 1.5-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish-white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly.
- 4Match the color rangeCompare against the expected color range: gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular, twinning common.
Often confused with
Metaköttigite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Metaköttigite leaves yellowish-white, Köttigite leaves white to reddish white; luster reads pearly on Metaköttigite and silky on cleavages on Köttigite.
How to tell apart: Streak differs, so Metaköttigite leaves yellowish-white, Symplesite leaves pale bluish; luster reads pearly on Metaköttigite and vitreous to oily, pearly on cleavages on Symplesite.
Often found alongside metaköttigite
Minerals reported to co-occur with metaköttigite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Zn,Fe)₃(AsO₄)₂·8(H₂O,OH)
- Mohs hardness
- 1.5-2.5
- Density
- 3.03 g/cm³
- Colors
- Streak
- Yellowish-white
- Luster
- Pearly
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular, twinning common
- Cleavage
- {110}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral from the oxide zone of an arsenic-rich polymetallic mineral deposit, formed by oxidation and concomitant dehydrogenization of ferroan köttigite
Where rockhounds find metaköttigite
Classic worldwide localities
- Ojuela mine, Mapimí, Durango, Mexico
Field-hunting tip
Where it forms: A rare secondary mineral from the oxide zone of an arsenic-rich polymetallic mineral deposit, formed by oxidation and concomitant dehydrogenization of ferroan köttigite. If you start seeing köttigite, smithsonite, adamite in float, you are in the right ground. Typical habit: tabular, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify metaköttigite?+
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Is metaköttigite safe to handle?+
What rocks look like metaköttigite?+
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Find metaköttigite on the map
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