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 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kaňkite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Kaňkite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microcrystalline crusts, fibrous aggregates, powdery coatings.
Often confused with
Kaňkite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 2); streak differs — Kaňkite leaves yellow, Scorodite leaves white; luster reads vitreous on Kaňkite and vitreous to sub-adamantine on Scorodite.
How to tell apart: Streak differs — Kaňkite leaves yellow, Pharmacosiderite leaves white; luster reads vitreous on Kaňkite and adamantine 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
- Density
- 2.83 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microcrystalline Crusts, Fibrous Aggregates, Powdery Coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Arsenic-rich Ore Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find kaňkite
Classic worldwide localities
- Kaňk, Czech Republic
- Jáchymov, Czech Republic
- Wittichen, Germany
Field-hunting tip
Look in oxidized hydrothermal arsenic-rich ore deposits country — that is the host setting where kaňkite typically forms. If you start seeing arsenopyrite, pitticite, scorodite in float, you are in the right ground. Field specimens usually show a microcrystalline crusts, fibrous aggregates, powdery coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kaňkite?+
Where is kaňkite found?+
How much is kaňkite worth?+
Is kaňkite safe to handle?+
What rocks look like kaňkite?+
What minerals are found with kaňkite?+
What kind of rock does kaňkite form in?+
What is kaňkite used for?+
Find kaňkite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
