Georgbokiite is a rare copper selenium oxide that forms chestnut-brown to dark brown complex equant to short prismatic crystals. It is a rare fumarolic sublimate. It was first described from Tolbachik fissure volcano, Kamchatka Peninsula, Russia.
Is this georgbokiite?
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 georgbokiite with a known reference. Georgbokiite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: chestnut brown, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: euhedral crystals, microscopic crystals.
Often confused with
Georgbokiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Georgbokiite is noticeably harder (Mohs 4 vs. 2); streak differs, so Georgbokiite leaves yellowish brown, Selenium leaves red; luster reads vitreous to adamantine on Georgbokiite and metallic on Selenium.
How to tell apart: Georgbokiite is noticeably harder (Mohs 4 vs. 2-2.5); streak differs, so Georgbokiite leaves yellowish brown, Chalcomenite leaves light blue.
Often found alongside georgbokiite
Minerals reported to co-occur with georgbokiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₅O₂(Se⁴⁺O₃)₂Cl₂
- Mohs hardness
- 4
- Density
- 4.88 g/cm³
- Colors
- Chestnut brownDark brown
- Streak
- Yellowish brown
- Luster
- Vitreous to adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Euhedral crystals, microscopic crystals
- Cleavage
- Perfect on {100} and {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare fumarolic sublimate
Where rockhounds find georgbokiite
Classic worldwide localities
- Tolbachik fissure volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: A rare fumarolic sublimate. If you start seeing burnsite, chloromenite, sofiite in float, you are in the right ground. Typical habit: euhedral crystals, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify georgbokiite?+
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What rocks look like georgbokiite?+
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Find georgbokiite on the map
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