Polylithionite (inclusions in Pollucite)
Current inventory:  0 gems
 

  
Polylithionite is named from the Greek word poly meaning many or much, in allusion to its composition with a high LITHIum content.

Discovered in 1884; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

KLi₂AlSi₄O₁₀ (F,OH)₂

Potassium Lithium Aluminum Silicate Fluoride

Molecular Weight:

393.12 gm

Composition:

Potassium

9.95 %

K

11.98 %

K₂O

Sodium

1.75 %

Na

2.36 %

Na₂O

Lithium

3.00 %

Li

6.46 %

Li₂O

Aluminum

6.86 %

Al

12.97 %

Al₂O₃

Silicon

28.58 %

S

61.14 %

SiO₂

Hydrogen

0.26 %

H

2.29 %

H₂O

Oxygen

44.77 %

O

Fluorine

4.83 %

F

4.83 %

F

—

 —  %

F

-O=F₂

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/H.11-10

Nickel-Strunz 10th Ed. ID:

9.EC.20

9 : SILICATES (Germanates)
E : Phyllosilicates
C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets

Related to:

Mica Group. Polylithionite-Trilithionite Series.

Members of Group:

Mica Group: Aluminoceldonite, Anandite, Annite, Annite-Phlogopite Series, Aspidolite, Balestraite, Biotite, Bityite, Boromuscovite, Brammallite, Celadonite, Chernykhite, Chromceladonite, Chromphyllite, Clintonite, Eastonite, Ephesite, Ferroaluminoceladonite, Ferroceladonite, Ferrokinoshitalite, Fluorannite, Fluorphlogopite, Ganterite, Glauconite, Hendricksite, Illite, Kinoshitalite, Lepidolite, Luanshiweiite, Margarite, Masutomilite, Montdorite, Muscovite, Muscovite-Celadonite Series, Nanpingite, Natro-glauconite, Norrishite, Oxykinoshitalite, Oxyphlogopite, Paragonite, Phengite, Phlogopite, Polylithionite, Preiswerkite, Roscoelite, Shirokshinite, Shirozulite, Siderophyllite, Sokolovaite, Suhailite, Tainiolite, Tetraferriannite, Tetraferriphlogopite, Tobelite, Trilithionite, Voloshinite, Wonesite, Yangzhumingite, Zinnwaldite

Varieties:

Cs-bearing Polylithionite

Synonyms:

ICSD 34336 (with F), PDF 21952

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Pseudohexagonal crystals, tabular || f001g, to 10 cm. As irregularly shaped aggregates of fine scaly crystals.

Twinning:

None

Physical Properties

Cleavage:

Perfect on {001} 

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

2.0 - 3.0

Density:

2.58 - 2.82 (g/cm³)

Luminescence:

May fluoresce lemon-yellow under SW UV

Radioactivity:

Barely Detectable; GRapi = 141.95 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Bright to pale pink, cream to white, colorless, pale brown to yellow-brown, bluish, greenish; in transmitted light, colorless

Transparency:

Transparent

Luster:

Pearly to waxy when fine-grained

Refractive Index:

1.530 - 1.559  Biaxial ( - )

Birefringence:

0.025 - 0.029

Dispersion:

Weak

Pleochroism:

n/a

Occurances

Geological Setting:

In irregular segregations and veinlets, as a late-stage and metasomatic replacement mineral, in syenite pegmatites in a differentiated alkalic massif (Lovozero massif, Russia).

Common Associations:

Microcline, Natrolite, Taeniolite, Steenstrupine, Aegirine, Analcime, Epistolite

Common Impurities:

Ti, Fe, Mn, Mg, Ca, Na, H₂O

Type Locality:

Kangerluarsuk Fjord (Kangerdluarssuq Fjord), Ilímaussaq complex, Narsaq, Kujalleq, Greenland

Year Discovered:

1884

View mineral photos:

Polylithionite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Polylithionite is named from the Greek word poly meaning many or much, in allusion to its composition with a high LITHIum content. Polylithionite is a member of the Mica Group of minerals that also includes Celadonite, Lepidolite, Muscovite  and Phlogopite. Polylithionite can often be found as attractive rosette crystal clusters resembling the petals of a flower and often associated ith Sérandite. Polylithionite is rarely available as a gemstone but a recent find in Pakistan has produced gemmy Pollucite crystals containing tiny crystal inclusions of Polylithionite. Magnification must be used to observe these tiny Polylithionite crystals which have good crystal forms. Polylithionite may fluoresce lemon yellow to pale yellowish white under shortwave UV light.

Locations for Polylithionite: On the Kangerdluarssuk Plateau and elsewhere in the Ilímaussaq intrusion, southern Greenland. In Russia, found on Mts. Karnasurt and Lepkhe-Nelm, Lovozero massif, Kola Peninsula. In the Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan. At Vøra, Sandefjord, Oslo region, Norway. From Mont Saint-Hilaire and near Saint-Amable, Quebec, Canada. In the USA, at Point of Rocks, Colfax County, New Mexico. On Mt. Malosa, Zomba district, Malawi.
 

  
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