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Eucryptite

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Foote Lithium Co. Mine (Foote Mine), Kings Mountain District, Cleveland Co., North Carolina, USA
© JBS 2006

Show Eucryptite Photos (9)
Formula:
LiAl[SiO
 
4
]
System:TrigonalColour:Colourless, white, tan, ...
Hardness:6½
Name:Named in 1880 by Brush and Dana from the Greek for "well concealed", in allusion to its occurrence embedded in albite.


Phenakite Group.

Classification of Eucryptite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/A.01-30
Nickel-Strunz 10th (pending) edition ID:9.AA.05

9 : SILICATES (Germanates)
A : Nesosilicates
A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
Dana 7th edition ID:51.1.1.3
Dana 8th edition ID:51.1.1.3

51 : NESOSILICATES Insular SiO4 Groups Only
1 : Insular SiO4 Groups Only with cations in [4] coordination
Hey's CIM Ref.:16.1.3

16 : Silicates Containing Aluminum and other Metals
1 : Aluminosilicates of Li
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Type Occurrence of Eucryptite

Type Locality:Abija N. Fillow Quarry (Branchville Quarry), Branchville, Redding, Fairfield Co., Connecticut, USA
Year of Discovery:1880

Occurrences of Eucryptite

Geological Setting:In lithium-rich pegmatites, often as graphic intergrowths with albite derived from alteration of spodumene.

Physical Properties of Eucryptite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Colourless, white, tan, grey.
Hardness (Mohs):6½
Cleavage:Poor/Indistinct
Indistinct on {101¯0} and {0001}.
Fracture:Conchoidal
Density (measured):2.657 - 2.666 g/cm3
Density (calculated):2.654 g/cm3

Crystallography of Eucryptite

Crystal System:Trigonal
Class (H-M):3 - Rhombohedral
Space Group:R3
Cell Parameters:a = 13.48Å, c = 9.01Å
Ratio:a:c = 1 : 0.668
Unit Cell Volume:V 1,417.87 ų (Calculated from Unit Cell)
Z:18
Morphology:Usually massive, less commonly in equant euhedral crystals with {101¯0}, {0001}, and {112¯0}.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
6.74 (60)
4.20 (30)
3.96 (100)
3.89 (40)
3.37 (90)
2.74 (80)
2.55 (60)

Optical Data of Eucryptite

Type:Uniaxial (+)
RI values: nω = 1.570 - 1.573 nε = 1.583 - 1.587
Maximum Birefringence:δ = 0.013

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low

Chemical Properties of Eucryptite

Formula:
LiAl[SiO
 
4
]
Essential elements:Al, Li, O, Si
All elements listed in formula:Al, Li, O, Si
Analytical Data:Bikita Zimbabwe and Kings Mountain, NC
Gelatinizes in acids
SiO2 (49.32), (47.97)
Al2O3 (40.43), 40.28)
Li2O (9.72), (11.45)
Na2O (0.24). (0.26)
K2O (0.01), 0
Common Impurities:Na,K

Relationship of Eucryptite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.AA.05Phenakite
Be
 
2
[SiO
 
4
]
9.AA.05Willemite
Zn
 
2
[SiO
 
4
]
9.AA.10Liberite
Li
 
2
Be[SiO
 
4
]
Related Minerals - Hey's Index Grouping:

- +
16.1.1Petalite
LiAlSi
 
4
O
 
10
16.1.2Spodumene
LiAl[Si
 
2
O
 
6
]
16.1.4Virgilite
LiAlSi
 
2
O
 
6
16.1.5Cookeite
LiAl
 
4
(Si
 
3
Al)O
 
10
(OH)
 
8
16.1.6Bikitaite
LiAlSi
 
2
O
 
6
·H
 
2
O
16.1.7Lunijianlaite
Li
 
0.7
Al
 
6.2
(Si
 
7
AlO
 
20
)(OH,O)
 
10
16.1.8Swinefordite
Li(Al,Li,Mg)
 
4
(Si,Al)
 
8
O
 
20
,(OH,F)
 
4
·xH
 
2
O
16.1.9Holmquistite
☐[Li
 
2
][Mg
 
3
Al
 
2
][(OH)
 
2
|Si
 
8
O
 
22
]
16.1.13Clinoferroholmquistite
[ ][Li
 
2
][Fe
2+
3
Al
 
2
][(OH)
 
2
|Si
 
8
O
 
22
]
16.1.14Magnesioholmquistite
16.1.15Bityite
CaLiAl
 
2
[(OH)
 
2
|BeAlSi
 
2
O
 
10
]
16.1.16Sogdianite
(K,Na)
 
2
(Li,Fe)
 
3
(Zr,Ti,Fe)Si
 
12
O
 
30
16.1.17Sugilite
KNa
 
2
(Fe,Mn,Al)
 
2
Li
 
3
Si
 
12
O
 
30
Related Minerals - Dana Grouping):

- +
51.1.1.1Phenakite
Be
 
2
[SiO
 
4
]
51.1.1.2Willemite
Zn
 
2
[SiO
 
4
]

Other Names for Eucryptite

Synonyms:
Lithionnephelin
Other Languages:
German:Eucryptit
Russian:Эвкриптит
Spanish:Eucryptita

Other Information

Fluorescence in UV light:Magenta-red or orange under SW UV.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Eucryptite

Reference List:Dana, E.S. (1892) Dana's System of Mineralogy, 6th. edition: 426.

Hurlbut, C.S., Jr. (1962) Eucryptite from Bikita, Southern Rhodesia. American Mineralogist: 47: 557-559.

Leavens, P.B., Hurlbut, C.S., Jr., and Nelen, J.A. (1968) Eucryptite and bikitaite from King's Mountain, North Carolina. American Mineralogist: 53: 1202-1207.

Černý, P. (1972) The Tanco pegmatite at Bernic Lake, Manitoba. VII. Eucryptite. Canadian Mineralogist: 11: 708-713.

Lahti, S.I., Kallio, P., von Knorring, O. (1982): The composition, physical properties and occurrence of eucryptite from the Haapaluoma pegmatite, Finland. Bull.Geol.Soc.Finland, 54, 1-2; 5-13.

Hesse, K.-F. (1985) Crystal structures of natural and synthetic α-eucryptite, LiAlSiO4. Zeitschrift für Kristallographie: 172: 147-151.

Anthony, Bideaux, Bladh & Nichols (1995), Handbook of Mineralogy, Vol. II.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana.

Zeitschrift für Kristallographie: 172: 147-151.

Internet Links for Eucryptite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Eucryptite in the Natural History Museum (London) online catalogue
  • Eucryptite details from Handbook of Mineralogy (PDF)
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    Localities for Eucryptite

    Hide Locality List
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Canada
     
    • Manitoba
      • Lac-du-Bonnet area
        • Bernic Lake
    China
     
    • Hunan Province
      • Chenzhou Prefecture
        • Linwu Co.
          • Xianghualing Sn-polymetallic ore field
    		Anthony, J.W. et al.: Handbook of Mineralogy
    • Xinjiang (Xinjiang-Uygur) Autonomous Region
      • Yili Hasake (Ili Kazakh) Autonomous Prefecture
        • Aletai (Altay) Prefecture
          • Fuyun Co.
            • Koktokay (Keketuohai) Pegmatite field
              • Altay Mine
    		Huanzhang Lu, Zhonggang Wang, and Yuansheng Li (1997): Chinese Journal of Geochemistry 16(1), 43-52.
    Finland
     
    • Länsi-Suomen Lääni
      • Vaasa
        • Peräseinäjoki
    		Lahti, S. I., Kallio, P. and von Knorring, O. (1982): The composition, physical properties and occurrence of eucryptite from the Haapaluoma pegmatite, Finland. Bull.Geol. Soc. Finland 54, 1-2, 5-13.
    Namibia
     
    • Erongo Region
      • Swakopmund District
        • Cape Cross area
    		http://www.mineral.tu-freiberg.de/econgeology/lehre/namibia/snlipegm/snlipegm_2_4.html
    Russia
     
    • Southern Siberia
      • Sayan Mts
        • Eastern Sayan
    		P.M. Kartashov data
    South Africa
     
    • Northern Cape Province
    		Minerals of South Africa
      • Namaqualand
        • Steinkopf
    		Minerals of South Africa
    Sweden
     
    • Södermanland
      • Stockholm
        • Haninge
    		Langhof, J., Jonson, E, Gustafsson, L. & Otter, B. (1998): Utö- en klassisk svensk mineralfyndort. Bergverksmuseets Skrift 14, 29-31
    UK
     
    • England
      • Devon
        • Okehampton area (Northern Dartmoor)
    		Fraudulent Kingsbury locality.
    USA
     
    • Arizona
      • Yavapai Co.
    		AmMin 67: 97-113 (1982)
          • Independence Gulch
    		Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 217; London, D. & D.M. Burt (1978), Lithium pegmatites of the White Picacho district, Maricopa and Yavapai Cos., AZ, in D.M. Burt and T.L. Péwé (editors), Guidebook to the geology of central Arizona, AZ Bur. Geol. Min. Tech. Spec. Paper 2: 61-72; London, D. & D.M. Burt (1982b), Lithium aluminosilicate occurrences in pegmatites and the aluminosilicate phase diagram, Am.Min.: 67: 483-509.
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 217; London, D. & D.M. Burt (1978), Lithium pegmatites of the White Picacho district, Maricopa and Yavapai Cos., AZ, in D.M. Burt and T.L. Péwé (editors), Guidebook to the geology of central AZ, AZ Bur. Geol. Min. Tech. Spec. Paper 2: 61-72; London, D. & D.M. Burt (1982b), Lithium aluminosilicate occurrences in pegmatites and the aluminosilicate phase diagram, Am.Min.: 67: 483-509.
    • Connecticut
      • Fairfield Co.
        • Redding
          • Branchville
    		AmMin 31:329-345 (1946)
      • Middlesex Co.
        • Portland
          • Collins Hill
    		Januzzi, 1976. Mineral Localities of Connecticut and Southeastern New York State (Taylor Assoc./Mineralogical Press)
    • Maine
      • Oxford Co.
        • Newry
    		King, V. and Foord, E., 1994, Mineralogy of Maine, v. 1.
    • New Hampshire
      • Strafford Co.
        • Strafford
          • Parker Mt
    		Rocks & Min.:64:504.
    • New Mexico
      • Taos Co.
        • Picuris District
    		Northrop, Minerals of New Mexico, 3rd Rev. Ed., 1996
    • North Carolina
      • Cleveland Co.
        • Kings Mountain District
    		Am Min 54 (1969), 1467-1469
    • South Dakota
      • Custer Co.
        • Custer District
          • Fourmile
    		Rocks & Minerals: 75(3): 156-169.
      • Pennington Co.
        • Keystone District
          • Keystone
    		Rocks & Minerals: 67(6): 380-388.
    Zimbabwe
     
    • Masvingo District
    		Zeolites of the World, Rudy W. Tschernich 1992
    Amer.Min.(1958) 43, 768-770
    Mineral and/or Locality
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