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| Lepidolite
was named in 1792 by Martin Klaproth from the Greek
words lepidos
for scale,
and lithos for stone, in allusion to its micaceous structure.
| Discovered
in 1792; IMA
status: Valid (pre-IMA; Grandfathered) |
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Chemistry
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Chemical
Formula: |
K(Li,Al)3(Si,Al)4O10(F,OH)2
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Potassium Lithium Aluminum Silicate Hydroxide Fluoride |
Molecular
Weight: |
388.30 gm |
Composition: |
Potassium |
10.07 % |
K |
12.13 % |
K2O |
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Lithium |
3.58 % |
Li |
7.70 % |
Li2O |
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Aluminum |
6.95 % |
Al |
13.13 % |
Al2O3 |
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Silicon |
28.93 % |
Si |
61.89 % |
SiO2 |
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Hydrogen |
0.26 % |
H |
2.32 % |
H2O |
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Oxygen |
45.32 % |
O |
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Fluorine |
4.89 % |
F |
4.89 % |
F |
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— % |
F |
—2.06 % |
—O=F2 |
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100.00 % |
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100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Silicates
(Germanates)
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Strunz 8th
Ed. ID:
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8/H.10-70
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Nickel-Strunz 10th
Ed. ID:
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9.EC.15
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9 : SILICATES (Germanates) E : Phyllosilicates C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
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Related
to: |
Mica
Group. Biotite Subgroup. Muscovite, Phlogopite, Polylithionite-Trilithionite
Series
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Members
of Group: |
Mica
Group: Aluminoceladonite, 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
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Varieties: |
Cs-rich
Lepidolite, Rb-rich Lepidolite
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Synonyms: |
Flower
Sugilite, Lavenderine, Lilalite, Lilianthite, Lithia
Mica, Lithionglimmer, Lithionite
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Crystal
Data
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Crystallography:
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Monoclinic
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Crystal
Habit:
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Tabular
to prismatic pseudohexagonal crystals, commonly with
rounded terminal faces, to 20 cm. In coarse to fine
scaly aggregates and massive.
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Twinning:
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Rare,
composition plane {001}, twin axis [310]
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Physical
Properties
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Cleavage: |
Perfect
{001}
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Fracture: |
Uneven
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Tenacity:
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Flexible,
elastic
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Moh's
Hardness: |
2.5
- 4.0
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Density:
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2.80
- 2.90 (g/cm3)
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Luminescence:
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May fluoresce medium intensity of creamy white to pale yellow;
sometimes yellow |
Radioactivity:
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Barely
Detectable;
GRapi = 143.68 (Gamma Ray American Petroleum Institute Units)
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Optical
Properties
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Color: |
Pink,
purple, rose-red, violet-gray, blue, yellowish, white, colorless;
colorless to pale pink in thin section
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Transparency: |
Translucent
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Luster: |
Vitreous,
Pearly
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Refractive
Index: |
1.525
- 1.587 Biaxial ( - )
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Birefringence: |
0.0290
- 0.0380
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Dispersion: |
Weak;
r > v
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Pleochroism: |
X
= almost colorless; Y
= Z
= pink, pale violet
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Occurances
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Geological
Setting: |
In
granite pegmatites, derived by metasomatic replacement
of muscovite or biotite; in some high-temperature quartz
veins, greisens, and granites. |
Common
Associations: |
Spodumene,
Elbaite, Amblygonite, Columbite, Cassiterite, Topaz,
Beryl, Micas |
Type
Locality: |
Rožná pegmatite, Ždár nad Sázavou, Vysocina Region, Moravia (Mähren; Maehren), Czech Republic
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Year
Discovered: |
1792 |
View
mineral photos: |
Lepidolite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com
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Lepidolite
was once considered to be a distinct mineral species
but has been redefined by the IMA
as a group of minerals and as part of the Polylithionite-Trilithionite
Series. The name Lepidolite is also used loosely
as a term for any light colored lithium-bearing mica
that has not been sufficiently analyzed for species
determination (ie., some "Lepidolite" may
actually be Muscovite or Phlogopite). Lepidolite is
a member of the Mica Group of minerals that also includes
Celadonite,
Muscovite, Phlogopite
and Polylithionite.
Lepidolite
is an uncommon mica and is an ore of lithium that forms
in huge masses that can contain substantial amounts
of lithium. Its typical pink to violet colors are one
of the only field tests to identify Lepidolite from
other micas although pink Muscovite or very pale Lepidolite
may complicate identification.
Lepidolite
is available from Rozná, near Bystrice, Czech Republic;
from Alabashka, Ural Mountains, Russia. In the Varuträsk
pegmatite, 15 km northwest of Skellefteĺ, Västerbotten,
Sweden. In the USA, at Mt. Mica, near Paris, Oxford
County, and Auburn, Androscoggin County, Maine; in the
Mesa Grande and Pala districts, San Diego County, California;
from the Brown Derby pegmatite, Gunnison County, Colorado;
in the Ingersoll mine, near Keystone, Pennington County,
South Dakota. From the Tanco mine, Bernic Lake, Manitoba,
Canada. At Maharitra, Mt. Bity, Madagascar. From Bikita,
Zimbabwe. In India, at Hazaribagh, Bihar. From the Virgem
da Lapa pegmatite, Minas Gerais, Brazil.
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Lepidolite
gems for sale:
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