Keyite is a rare copper-zinc arsenate mineral best known for its occurrence in the Tsumeb Mine. It typically forms as small, tabular deep sky-blue-colored crystals that are highly sought after by advanced collectors of rare species.
Is this keyite?
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 keyite with a known reference. Keyite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: azure.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, tabular.
Often confused with
Keyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads adamantine on Keyite and dull to vitreous on fractures on Duftite.
How to tell apart: Streak differs, so Keyite leaves pale blue, Conichalcite leaves green; luster reads adamantine on Keyite and vitreous to somewhat greasy on Conichalcite.
Often found alongside keyite
Minerals reported to co-occur with keyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (□₀.₅Cu₀.₅)CuCdZn₂(AsO₄)₃·H₂O
- Mohs hardness
- 3.5-4
- Density
- 4.95 g/cm³
- Colors
- Streak
- Pale blue
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, tabular
- Cleavage
- Good on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit
Where rockhounds find keyite
Classic worldwide localities
- Tsumeb, Namibia
Field-hunting tip
Where it forms: A secondary mineral in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit. If you start seeing cuprian adamite, schulténite, metazeunerite in float, you are in the right ground. Typical habit: prismatic, tabular. Train your eye for that shape before scanning the outcrop.
More keyite photos
Common questions
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Find keyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
