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
GUID
(UUID V4):
(UUID V4):
c5cd765a-e4cf-4828-bf56-5f1179d436db
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 |
---|---|---|
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 = 1.570 - 1.573 nε = 1.583 - 1.587
Max Birefringence:
δ = 0.013
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Low
Chemistry of Eucryptite
Mindat Formula:
LiAlSiO4
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) |
---|---|---|---|---|---|---|---|
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 | ||
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 | ||
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 | ||
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 | ||
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 | |
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 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
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Radiation - Copper Kα
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 this group:
Common Associates
Associated Minerals Based on Photo Data:
25 photos of Eucryptite associated with Spodumene | LiAlSi2O6 |
10 photos of Eucryptite associated with Scheelite | Ca(WO4) |
10 photos of Eucryptite associated with Quartz | SiO2 |
8 photos of Eucryptite associated with Albite | Na(AlSi3O8) |
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 Cookeite | (LiAl4◻)[AlSi3O10](OH)8 |
5 photos of Eucryptite associated with Chlorophane | CaF2 |
4 photos of Eucryptite associated with Pollucite | (Cs,Na)2(Al2Si4O12) · 2H2O |
4 photos of Eucryptite associated with Hsianghualite | Ca3Li2(Be3Si3O12)F2 |
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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References for Eucryptite
Reference List:
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
Localities for Eucryptite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Australia | |
| Jacobson et al. (2007) |
Canada | |
| 153-155. +4 other references |
| Blackburn C. et al (2002) |
Tindle et al. (2002) | |
China | |
| Anthony |
| Xudong Che et al. (2007) |
| Tianren Zou et al. (1986) +2 other references |
Egypt | |
| Gehad M. Saleh (2007) |
Finland | |
| Lahti +1 other reference |
| Lahti et al. (1982) |
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) |
| Novák (2009) |
Russia | |
| Pavel.M. Kartashov (n.d.) +2 other references |
| Zozulya et al. (2024) |
James Cheshire collection | |
South Africa | |
| Cairncross et al. (1995) |
| Cairncross et al. (1995) |
Spain | |
| Errandonea-Martin et al. (2022) |
| Roda-Robles et al. (2010) |
Encarnación Roda-Robles (2007) +1 other reference | |
Errandonea-Martin et al. (2022) | |
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 | |
| 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 et al. (1969) +2 other references |
| Staatz +4 other references |
| Rocks & Minerals: 67 (6) +1 other reference |
Zimbabwe | |
| Roland Schmidt Collection |
Tschernich (1992) +1 other reference | |
Hurlbut (1958) |
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Parker Mountain Mine, Parker Mountain, Strafford, Strafford County, New Hampshire, USA