Koritnigite is a rare secondary zinc arsenate mineral typically found as attractive, delicate, bladed crystal sprays in oxidized mining zones. It is most famous from the Tsumeb Mine in Namibia, where it occurs as a byproduct of the alteration of primary arsenides. Collectors should handle it with caution due to its arsenic content.
Is this koritnigite?
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 koritnigite with a known reference. Koritnigite sits at Mohs 2, 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: pearly on {010}.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: bladed to tabular crystals, often in radiating sprays or crusts.
Often confused with
Koritnigite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Legrandite is the harder of the two (Mohs 4.5 vs. 2); luster reads pearly on {010} on Koritnigite and vitreous on Legrandite.
How to tell apart: Hopeite is the harder of the two (Mohs 3.5 vs. 2); luster reads pearly on {010} on Koritnigite and vitreous, pearly on {010} cleavages on Hopeite.
How to tell apart: Parahopeite is the harder of the two (Mohs 3.5-4 vs. 2); luster reads pearly on {010} on Koritnigite and vitreous, pearly on cleavages on Parahopeite.
Often found alongside koritnigite
Minerals reported to co-occur with koritnigite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Zn(AsO₃OH)·H₂O
- Mohs hardness
- 2
- Density
- 3.54 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly on {010}
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Bladed to tabular crystals, often in radiating sprays or crusts
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral of the lower oxidation zone in a dolostone-hosted polymetallic hydrothermal ore deposit (Tsumeb, Namibia)
Where rockhounds find koritnigite
Classic worldwide localities
- Found at Tsumeb, Namibia
- Jáchymov (Joachimsthal), Czech Republic
- Richelsdorf, Hesse, Germany
Field-hunting tip
Where it forms: A secondary mineral of the lower oxidation zone in a dolostone-hosted polymetallic hydrothermal ore deposit (Tsumeb, Namibia). If you start seeing tennantite, cuprian adamite, stranskiite in float, you are in the right ground. Typical habit: bladed to tabular crystals, often in radiating sprays or crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify koritnigite?+
Where is koritnigite found?+
Is koritnigite safe to handle?+
What rocks look like koritnigite?+
What minerals are found with koritnigite?+
What kind of rock does koritnigite form in?+
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Find koritnigite on the map
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