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 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Georgbokiite leaves a yellowish brown streak.
- 3Read the lusterHold the specimen under a strong light. Georgbokiite typically shows a vitreous to adamantine luster.
- 4Match the color rangeCompare against the expected color range: chestnut-brown, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: complex equant to short prismatic 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 3-4 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: Streak differs, so Georgbokiite leaves yellowish brown, Chalcomenite leaves pale blue; luster reads vitreous to adamantine on Georgbokiite and vitreous on Chalcomenite.
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
- 3-4
- Density
- 4.88 g/cm³
- Colors
- Streak
- Yellowish Brown
- Luster
- Vitreous to Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Complex Equant to Short Prismatic Crystals
- Cleavage
- Perfect On {100} and {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumaroles
Where rockhounds find georgbokiite
Classic worldwide localities
- Tolbachik volcano, Kamchatka, Russia
Field-hunting tip
Look in fumaroles country, the host setting where georgbokiite typically forms. If you start seeing selenium, chloromenite, euchlorine in float, you are in the right ground. Field specimens usually show a complex equant to short prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find georgbokiite on the map
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