Kuznetsovite is a rare mercury-arsenic oxychloride mineral that typically forms small, distinct tetrahedral crystals. It is primarily found in the unique hydrothermal environment of the Khaidarkan mercury-antimony deposit. Due to its toxic mercury and arsenic content and extreme rarity, it is sought after primarily by advanced mineral collectors.
Is this kuznetsovite?
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 kuznetsovite with a known reference. Kuznetsovite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: yellow brown, honey brown, light brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: tetrahedral crystals, massive.
Often confused with
Kuznetsovite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kuznetsovite leaves yellow-orange, Cinnabar leaves scarlet; luster reads vitreous to adamantine on Kuznetsovite and adamantine, inclining to metallic when dark; dull in friable material on Cinnabar.
How to tell apart: Streak differs, so Kuznetsovite leaves yellow-orange, Kleinite leaves sulfur-yellow; luster reads vitreous to adamantine on Kuznetsovite and adamantine to greasy on Kleinite.
Often found alongside kuznetsovite
Minerals reported to co-occur with kuznetsovite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₃AsO₄Cl
- Mohs hardness
- 2.5-3
- Density
- 8.64-8.82 g/cm³
- Colors
- Streak
- Yellow-orange
- Luster
- Vitreous to adamantine
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Tetrahedral crystals, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidation zone of hydrothermal mercury deposits
Where rockhounds find kuznetsovite
Classic worldwide localities
- Arzak mercury deposit, Pii-Khem district, Tuva, and the Kelyan Sb–Hg deposit, Buryatia, Siberia, Russia
- Khaydarkan mercury deposit, Fergana Valley, Alai Range, Kyrgyzstan
Field-hunting tip
Where it forms: In the oxidation zone of hydrothermal mercury deposits. If you start seeing cinnabar, calomel, eglestonite in float, you are in the right ground. Typical habit: tetrahedral crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find kuznetsovite on the map
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