Eucryptite
A valid IMA mineral species - grandfathered
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About Eucryptite
Formula:
LiAlSiO4
Colour:
Colorless, white, pale tan, pale gray
Lustre:
Sub-Vitreous, Resinous, Greasy
Hardness:
6½
Specific Gravity:
2.657 - 2.666
Crystal System:
Trigonal
Member of:
Name:
Named in 1880 by Brush and Dana from the Greek for "well concealed", in allusion to its occurrence embedded in albite. Also known as α-eucryptite or alpha-eucryptite.
Unique Identifiers
Mindat ID:
1419
Long-form identifier:
mindat:1:1:1419:5
IMA Classification of Eucryptite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1880
Classification of Eucryptite
9.AA.05
9 : SILICATES (Germanates)
A : Nesosilicates
A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
Dana 7th ed.:
51.1.1.3
51.1.1.3
51 : NESOSILICATES Insular SiO4 Groups Only
1 : Insular SiO4 Groups Only with cations in [4] coordination
51 : NESOSILICATES Insular SiO4 Groups Only
1 : Insular SiO4 Groups Only with cations in [4] coordination
16.1.3
16 : Silicates Containing Aluminum and other Metals
1 : Aluminosilicates of Li
16 : Silicates Containing Aluminum and other Metals
1 : Aluminosilicates of Li
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ecp | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Ecr | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Eucryptite
Sub-Vitreous, Resinous, Greasy
Transparency:
Transparent, Translucent
Comment:
Usually sub-vitrous
Colour:
Colorless, white, pale tan, pale gray
Streak:
White
Hardness:
6½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Poor/Indistinct
Poor on {1010} and {0001}.
Poor on {1010} and {0001}.
Fracture:
Irregular/Uneven, Conchoidal
Comment:
Pure masses from Bikita show conchoidal fracture.
Density:
2.657 - 2.666 g/cm3 (Measured) 2.654 g/cm3 (Calculated)
Optical Data of Eucryptite
Type:
Uniaxial (+)
RI values:
nω = 1.57 - 1.573 nε = 1.583 - 1.587
Max. Birefringence:
δ = 0.013 - 0.014
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Eucryptite
Mindat Formula:
LiAlSiO4
Element Weights:
Elements listed:
Common Impurities:
Na,K
Crystallography of Eucryptite
Crystal System:
Trigonal
Class (H-M):
3 - Rhombohedral
Space Group:
R3
Setting:
R3
Cell Parameters:
a = 13.48 Å, c = 9.01 Å
Ratio:
a:c = 1 : 0.668
Unit Cell V:
1,417.87 ų (Calculated from Unit Cell)
Z:
18
Morphology:
Usually massive, rarely in equant euhedral crystals with {1010}, {0001}, and {1120}. (Bikita: Hurlbut, 1962). More complex crystals found at Kings Mountain, North Carolina, USA.
Twinning:
Some eucryptite samples are polysynthetically twinned, with alternating thin and broad twin lamellae. Sometimes possible to recognize the twinning with the naked eye. The angle between the optic axes of two adjacent crystals is about 74° and the angle between the composition plane of the crystals and the optic axis 37°.
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0010937 | Eucryptite | Hesse K F (1985) Crystal structures of natural and synthetic alpha-eucryptite, LiAlSiO4 Zeitschrift fur Kristallographie 172 147-151 |  | 1985 | Zimbabwae | 0 | 293 |
| 0010936 | Eucryptite | Hesse K F (1985) Crystal structures of natural and synthetic alpha-eucryptite, LiAlSiO4 Zeitschrift fur Kristallographie 172 147-151 | | 1985 | synthetic | 0 | 293 |
| 0000376 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 296 | |
| 0002631 | Eucryptite | Daniels P, Fyfe C A (2001) Al, Si order in the crystal structure of alpha-eucryptite (LiAlSiO4) Not the correct model American Mineralogist 86 279-283 | | 2001 | 0 | 293 | |
| 0002630 | Eucryptite | Daniels P, Fyfe C A (2001) Al, Si order in the crystal structure of alpha-eucryptite (LiAlSiO4) American Mineralogist 86 279-283 | | 2001 | 0 | 293 | |
| 0000377 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 473 | |
| 0000378 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 608 | |
| 0000379 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 713 | |
| 0000380 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 757 | |
| 0000381 | Eucryptite | Pillars W W, Peacor D R (1973) The crystal structure of beta eucryptite as a function of temperature American Mineralogist 58 681-690 | | 1973 | 0 | 920 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.74 Å | (60) |
| 4.20 Å | (30) |
| 3.96 Å | (100) |
| 3.89 Å | (40) |
| 3.37 Å | (90) |
| 2.74 Å | (80) |
| 2.55 Å | (60) |
| 2.38 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
In lithium-rich pegmatites, often as graphic intergrowths with albite derived from alteration of spodumene.
Type Occurrence of Eucryptite
General Appearance of Type Material:
Compact masses with an indistinct fibrous to columnar structure.
Place of Conservation of Type Material:
No designated type specimen.
Geological Setting of Type Material:
Lithium-rich pegmatite.
Associated Minerals at Type Locality:
Synonyms of Eucryptite
Other Language Names for Eucryptite
Relationship of Eucryptite to other Species
Member of:
Other Members of Phenakite Group:
Common Associates
Associations Based on Photo Data:
| 29 photos of Eucryptite associated with Spodumene | LiAlSi2O6 |
| 16 photos of Eucryptite associated with Scheelite | Ca(WO4) |
| 11 photos of Eucryptite associated with Quartz | SiO2 |
| 10 photos of Eucryptite associated with Hsianghualite | Ca3Li2(Be3Si3O12)F2 |
| 9 photos of Eucryptite associated with Albite | Na(AlSi3O8) |
| 8 photos of Eucryptite associated with Cookeite | (LiAl4◻)[AlSi3O10](OH)8 |
| 7 photos of Eucryptite associated with Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| 6 photos of Eucryptite associated with Calcite | CaCO3 |
| 5 photos of Eucryptite associated with 'Chlorophane' | CaF2 |
| 4 photos of Eucryptite associated with Lepidolite |
Related Minerals - Strunz-mindat Grouping
Fluorescence of Eucryptite
Magenta-red or orange under SW UV. Generally fluorescent (both natural and synthetic), however, Haapaluoma eucryptite is not fluorescent. The fluorescence of Tanco eucryptite fades rapidly after the larger grains have been crushed and disappears completely in powdered material (Cerny 1972).
Other Information
Notes:
Gelatinizes with HCl.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Eucryptite
mindat.org URL:
https://www.mindat.org/min-1419.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Eucryptite
Reference List:
ROY, RUSTUM, ROY, DELLA M., OSBORN, E. F. (1950) Compositional and Stability Relationships Among the Lithium Aluminosilicates: Eucryptite, Spodumene, and Petalite. Journal of the American Ceramic Society, 33 (5). 152-159 doi:10.1111/j.1151-2916.1950.tb12780.x
Winkler, Helmut G. F. (1954) Struktur und Polymorphie des Eukryptits (Tief-LiAlSiO4). (Betrachtungen zur Polymorphie II.). Heidelberger Beiträge zur Mineralogie und Petrographie, 4 (1-2). 233-242 doi:10.1007/bf01111159
Hurlbut, Cornelius S. (1962) Eucryptite from Bikita, Southern Rhodesia. American Mineralogist, 47 (5-6) 557-561
Leavens, Peter B., Hurlbut, C. S., Nelen, and Joseph A. (1968) Eucryptite and bikitaite from King's Mountain, North Carolina. American Mineralogist, 53 (7-8) 1202-1207
Černý, P. (1972) The Tanco pegmatite at Bernic Lake, Manitoba. VII. Eucryptite. The Canadian Mineralogist, 11 (3) 708-713
LEISMANN, D.; BÖHM, H.; HOFFMANN, W. (1976) Doppelbrechung und optisches Drehungsvermögen von ß-Eukryptit, LiAlSiO4. Zeitschrift für Kristallographie, 143 (1-6). 300-308 doi:10.1524/zkri.1976.143.jg.300
Lahti, S.I., Kallio, P., von Knorring, O. (1982) The composition, physical properties and occurrence of eucryptite from the Haapaluoma pegmatite, Finland. Bulletin of the Geological Society of Finland, 54 (1) 5-13 doi:10.17741/bgsf/54.1-2.001
Hesse, K.-F. (1985) Crystal structures of natural and synthetic α-eucryptite, LiAlSiO4. Zeitschrift für Kristallographie, 172 (1). 147-151 doi:10.1524/zkri.1985.172.1-2.147
Norby, P.; Hanson, J. C.; Fitch, A. N.; Vaughan, G.; Flaks, L.; Gualtieri, A. (2000) Formation of α-Eucryptite, LiAlSiO4: An In-Situ Synchrotron X-ray Powder Diffraction Study of a High Temperature Hydrothermal Synthesis. Chemistry of Materials, 12 (5). 1473-1479 doi:10.1021/cm991210h
Localities for Eucryptite
Showing 53 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Australia | |
| Jacobson et al. (2007) |
| Simone Conti Collection |
Canada | |
| 153-155. +6 other references |
| Blackburn C. et al (2002) |
| Avalon Advanced Materials Inc. | |
China | |
| Anthony |
| Xudong Che et al. (2007) +1 other reference |
| Luo et al. (2026) |
| Luo et al. (2026) | |
| 何晗晗; 艾尔肯; 吐尔孙; 王登红; 王瑞江; 陈振宇 (2020) |
| Tianren Zou et al. (1986) +2 other references |
Egypt | |
| Saleh (2007) |
Finland | |
| Lahti +1 other reference |
| Lahti et al. (1982) +1 other reference |
Kazakhstan | |
| Oitseva et al. (2017) |
Namibia | |
| www.mineral.tu-freiberg.de (2003) |
| Keller (1991) +1 other reference | |
| von Bezing (2007) |
| Baldwin (1994) |
Poland | |
| Pieczka et al. (2012) |
Portugal | |
| Errandonea-Martin et al. (2022) |
| Garate-Olave et al. (2024) |
| Novák et al. (2009) |
Russia | |
| Pavel M. Kartashov (n.d.) +2 other references |
| Zozulya et al. (2024) |
| James Cheshire collection | |
Rwanda | |
| Acke et al. (2025) |
South Africa | |
| Cairncross et al. (1995) |
| Cairncross et al. (1995) |
Spain | |
| Errandonea-Martin et al. (2022) |
| Errandonea-Martin et al. (2022) |
| Roda-Robles et al. (2010) | |
| Encarnación Roda-Robles (2007) +1 other reference | |
Sweden | |
| Langhof et al. (1998) |
UK | |
| Fraudulent Kingsbury locality. |
USA | |
| AmMin 67: 97-113 (1982) |
| London (1978) +2 other references |
| London (1978) +2 other references | |
| former Ronald Januzzi collection. |
| Ronald Januzzi collection +4 other references |
| Ralph Lieser of Pappy’s Beryl Shop +3 other references |
| King et al. (1994) |
| Rocks & Min.:64:504. +1 other reference |
| Jahns et al. (1977) +1 other reference |
| London et al. (1982) |
| White (1969) +2 other references |
| Staatz +4 other references |
| Rocks & Minerals: 67 (6) +1 other reference |
Zimbabwe | |
| Martin (2020) |
| Sibanda (2020) +1 other reference |
| Roland Schmidt Collection |
| Tschernich (1992) +1 other reference | |
| Hurlbut (1958) |
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Parker Mountain Mine, Strafford, Strafford County, New Hampshire, USA