Kaňkite is a rare secondary arsenic mineral that forms as an oxidation product of arsenopyrite. It is typically found as small, vibrant yellow to yellowish-green earthy crusts or fibrous tufts within weathered ore dumps and mine workings.
Is this kaňkite?
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 kaňkite with a known reference. Kaňkite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to vitreous.
- 4Match the color rangeCompare against the expected color range: yellow green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, encrustations.
Often confused with
Kaňkite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kaňkite leaves grayish yellow, Scorodite leaves greenish white; luster reads dull to vitreous on Kaňkite and vitreous to subadamantine, subresinous on Scorodite.
How to tell apart: Streak differs, so Kaňkite leaves grayish yellow, Pharmacosiderite leaves yellowish green; luster reads dull to vitreous on Kaňkite and adamantine to greasy on Pharmacosiderite.
Often found alongside kaňkite
Minerals reported to co-occur with kaňkite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeAsO₄·3.5H₂O
- Mohs hardness
- 2-3
- Density
- 2.60-2.70 g/cm³
- Colors
- Streak
- Grayish yellow
- Luster
- Dull to vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, encrustations
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in highly weathered mine dumps containing arsenopyrite (Kaňk, Czech Republic)
Where rockhounds find kaňkite
Classic worldwide localities
- Šafary and Kuntery mine dumps, near Kaňk, Kutná Hora district, and in the Svornost mine, Jáchymov (Joachimsthal), Czech Republic
- Munzig, near Meissen, and at Brand-Erbisdorf, Saxony, Germany
- Menzenschwand, Black Forest, Germany
- King’s Wood mine, Buckfastleigh, Devon, and from the South Terras mine, St. Stephen-in-Brannel, Cornwall, England
- Suzukura mine, seven km north-northeast of Enzan, Yamanashi Prefecture, Japan
Field-hunting tip
Where it forms: A rare secondary mineral in highly weathered mine dumps containing arsenopyrite (Kaňk, Czech Republic). If you start seeing scorodite, pitticite, parascorodite in float, you are in the right ground. Typical habit: botryoidal, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
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Find kaňkite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
