Kuliokite-(Y) is an extremely rare yttrium-rich silicate mineral primarily found in alkaline pegmatites of the Kola Peninsula. It typically occurs as small, pale yellow to brownish tabular crystals or granular masses, often associated with other rare earth minerals.
Is this kuliokite-(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 kuliokite-(y) with a known reference. Kuliokite-(Y) sits at Mohs 4-5, 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: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, white, light pink.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy.
Often confused with
Kuliokite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kuliokite-(Y) leaves white, Allanite leaves gray; luster reads adamantine on Kuliokite-(Y) and submetallic on Allanite.
How to tell apart: Epidote is the harder of the two (Mohs 6-7 vs. 4-5); streak differs, so Kuliokite-(Y) leaves white, Epidote leaves grayish white; luster reads adamantine on Kuliokite-(Y) and vitreous, pearly, somewhat resinous on Epidote.
Often found alongside kuliokite-(y)
Minerals reported to co-occur with kuliokite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y₄Al(SiO₄)₂(OH)₂F₅
- Mohs hardness
- 4-5
- Density
- 4.3 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Platy
- Cleavage
- Poor on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As inclusions in fluorite or on fissures in microcline pegmatites
Where rockhounds find kuliokite-(y)
Classic worldwide localities
- Mt. Ploskaya, Keivy massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: As inclusions in fluorite or on fissures in microcline pegmatites. If you start seeing thalenite, xenotime, kainosite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kuliokite-(y)?+
Where is kuliokite-(y) found?+
What rocks look like kuliokite-(y)?+
What minerals are found with kuliokite-(y)?+
What kind of rock does kuliokite-(y) form in?+
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Find kuliokite-(y) on the map
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