Sosedkoite is an exceptionally rare potassium-aluminum-tantalum oxide mineral found in complex granite pegmatites. It typically occurs as small, distinct colorless tabular crystals associated with other rare tantalum species.
Is this sosedkoite?
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 sosedkoite with a known reference. Sosedkoite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, inclusions.
Often found alongside sosedkoite
Minerals reported to co-occur with sosedkoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₅Al₂Ta₂₂O₆₀
- Mohs hardness
- 6
- Density
- 6.9 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a granite pegmatite
Where rockhounds find sosedkoite
Classic worldwide localities
- Mt. Vasin-Myl’k, Voron’i massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In a granite pegmatite. If you start seeing microlite, simpsonite, cesstibtantite in float, you are in the right ground. Typical habit: acicular, inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sosedkoite?+
Where is sosedkoite found?+
What minerals are found with sosedkoite?+
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Find sosedkoite on the map
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