Polylithionite is a lithium-rich mica typically found in silica-undersaturated alkaline rocks and pegmatites. It often forms thin, platy, or tabular crystals that exhibit the classic perfect basal cleavage of the mica group, though it is usually identified by its association with rare alkaline minerals like Eudialyte.
Is this polylithionite?
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 polylithionite with a known reference. Polylithionite sits at Mohs 2-3, 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: pearly to waxy when fine-grained.
- 4Match the color rangeCompare against the expected color range: colorless, bluish, violet, greenish, pearl white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pseudo hexagonal, scaly, tabular.
Often confused with
Polylithionite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside polylithionite
Minerals reported to co-occur with polylithionite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KLi₂AlSi₄O₁₀F₂
- Mohs hardness
- 2-3
- Density
- 2.58-2.82 g/cm³
- Streak
- White
- Luster
- Pearly to waxy when fine-grained
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Pseudo hexagonal, scaly, tabular
- Cleavage
- {001}, perfect
- Fluorescence
- An yellow-lemon under SW UV
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- In irregular segregations and veinlets, as a late-stage and metasomatic replacement mineral, in syenite pegmatites in a differentiated alkalic massif (Lovozero massif, Russia)
Where rockhounds find polylithionite
Classic worldwide localities
- Point of Rocks, Colfax Co., New Mexico, USA
- Found on Mts. Karnasurt and Lepkhe-Nelm, Lovozero massif, Kola Peninsula, Russia
- Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan
- Vøra, Sandefjord, Oslo region, Norway
- Mont Saint-Hilaire and near Saint-Amable, Quebec, Canada
- Mt. Malosa, Zomba district, Malawi
Field-hunting tip
Where it forms: In irregular segregations and veinlets, as a late-stage and metasomatic replacement mineral, in syenite pegmatites in a differentiated alkalic massif (Lovozero massif, Russia). If you start seeing microcline, natrolite, taeniolite in float, you are in the right ground. Typical habit: pseudo hexagonal, scaly, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify polylithionite?+
Where is polylithionite found?+
What rocks look like polylithionite?+
What minerals are found with polylithionite?+
What kind of rock does polylithionite form in?+
What is polylithionite used for?+
Find polylithionite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
