Lazarenkoite is a very rare arsenic-bearing mineral often found as small, yellow, platy or micaceous crystals. It is primarily identified in hydrothermal deposits associated with primary arsenic minerals like arsenopyrite. Due to its extreme rarity and arsenic content, it is primarily sought by advanced mineral collectors specializing in rare species.
Is this lazarenkoite?
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 lazarenkoite with a known reference. Lazarenkoite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to silky.
- 4Match the color rangeCompare against the expected color range: light orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: encrustations, fibrous.
Often confused with
Lazarenkoite vs. its common look-alikes, and how to tell them apart in the field.

How to tell apart: Pharmacosiderite is the harder of the two (Mohs 2.5 vs. 1); streak differs, so Lazarenkoite leaves light yellow, Pharmacosiderite leaves yellowish green; luster reads resinous to silky on Lazarenkoite and adamantine to greasy on Pharmacosiderite.

How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 1); streak differs, so Lazarenkoite leaves light yellow, Scorodite leaves greenish white; luster reads resinous to silky on Lazarenkoite and vitreous to subadamantine, subresinous on Scorodite.
Often found alongside lazarenkoite
Minerals reported to co-occur with lazarenkoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaFeAs₃O₇·3H₂O
- Mohs hardness
- 1
- Density
- 3.450 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Resinous to silky
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Encrustations, fibrous
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidation zone of a metallic ore deposit
Where rockhounds find lazarenkoite
Classic worldwide localities
- Khovu-Aksy Ni–Co deposit, Tuva, Siberia, Russia
Field-hunting tip
Where it forms: In the oxidation zone of a metallic ore deposit. If you start seeing annabergite, skutterudite, löllingite in float, you are in the right ground. Typical habit: encrustations, fibrous. Train your eye for that shape before scanning the outcrop.



