Polyakovite-(Ce) is a rare member of the perrierite group found primarily in alkaline pegmatites. It is typically identified as small, dark, submetallic tabular crystals that are often radioactive due to their thorium content.
Is this polyakovite-(ce)?
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 polyakovite-(ce) with a known reference. Polyakovite-(Ce) sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: amorphous, euhedral crystals, metamict.
Often confused with
Polyakovite-(Ce) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Polyakovite-(Ce) leaves light brown, Allanite leaves gray; luster reads vitreous on Polyakovite-(Ce) and submetallic on Allanite.
How to tell apart: Streak differs, so Polyakovite-(Ce) leaves light brown, Perrierite-(Ce) leaves brown; luster reads vitreous on Polyakovite-(Ce) and resinous, lustrous to dull on Perrierite-(Ce).
Often found alongside polyakovite-(ce)
Minerals reported to co-occur with polyakovite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ce,Ca)₄MgCr₂(Ti,Nb)₂Si₄O₂₂
- Mohs hardness
- 5.5-6
- Density
- 4.75 g/cm³
- Colors
- Streak
- Light brown
- Luster
- Vitreous
- Transparency
- Translucent in thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Amorphous, euhedral crystals, metamict
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a carbonatite vein cutting phlogopite-fluororichterite rock
Where rockhounds find polyakovite-(ce)
Classic worldwide localities
- N97 mine, Ilmen Natural Reserve, southern Urals, Russia
Field-hunting tip
Where it forms: In a carbonatite vein cutting phlogopite-fluororichterite rock. If you start seeing calcite, dolomite, fluororichterite in float, you are in the right ground. Typical habit: amorphous, euhedral crystals, metamict. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify polyakovite-(ce)?+
Where is polyakovite-(ce) found?+
Is polyakovite-(ce) safe to handle?+
What rocks look like polyakovite-(ce)?+
What minerals are found with polyakovite-(ce)?+
What kind of rock does polyakovite-(ce) form in?+
What is polyakovite-(ce) used for?+
Find polyakovite-(ce) on the map
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