Kapitsaite-(Y) is an extremely rare silicate mineral found in the unique alkaline pegmatites of the Dara-i-Pioz massif in Tajikistan. It typically occurs as small yellowish-pale pink tabular crystals associated with other rare REE-bearing silicates and borosilicates.
Is this kapitsaite-(y)?
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 kapitsaite-(y) with a known reference. Kapitsaite-(Y) sits at Mohs 5, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: light pink, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: aggregates, wheat sheaf.
Often confused with
Kapitsaite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kapitsaite-(y)
Minerals reported to co-occur with kapitsaite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₄Y₂Si₈B₄O₂₈F
- Mohs hardness
- 5
- Density
- 3.74 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Aggregates, wheat sheaf
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a boulder of peralkaline pegmatite in the moraine of a glacier
Where rockhounds find kapitsaite-(y)
Classic worldwide localities
- Darii-Pioz glacier, Alayskiy Range, Garm region, northern Tajikistan
Field-hunting tip
Where it forms: In a boulder of peralkaline pegmatite in the moraine of a glacier. If you start seeing quartz, reedmergnerite, leucosphenite in float, you are in the right ground. Typical habit: aggregates, wheat sheaf. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kapitsaite-(y)?+
Where is kapitsaite-(y) found?+
What rocks look like kapitsaite-(y)?+
What minerals are found with kapitsaite-(y)?+
What kind of rock does kapitsaite-(y) form in?+
What is kapitsaite-(y) used for?+
Find kapitsaite-(y) on the map
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