Hexacelsian
A valid IMA mineral species
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About Hexacelsian
Anders Celsius
Formula:
BaAl2Si2O8
Colour:
Colorless
Lustre:
Vitreous
Hardness:
4½ - 6
Specific Gravity:
3.305 (Calculated)
Crystal System:
Hexagonal
Member of:
Name:
The name given to the mineral matches the historical name used for the synthetic material. It is the hexagonal polymorph of celsian. The root name honors Anders Celsius (27 November 1701 Uppsala, Sweden - 25 April 1744 Uppsala, Sweden], astronomer, physicist, and naturalist. He had the Astronomical Observatory built and he experimented with standardizing temperature measurements. The Celsius temperature scale is also named in his honor.
Type Locality:
Polymorph of:
High-temperature polymorph.
Known as a synthetic compound (disordered β-BaAl2Si2O8).
An analogue of synthetic low-temperature α-hexacelsian. The hexacelsian structure (polytype 2H) is formed by double layers of tetrahedra linked by their tops and bases, which are parallel to (001). Each layer is built from hexagonal (ditrigonal) rings of tetrahedra. The tetrahedra in rings with a disordered Al/Si distribution are rotated by approximately 14.5° compared to the position of the tetrahedra in ideal hexagonal rings in the high-temperature γ-hexacelsian. Every second layer in the structure of the studied hexacelsian is rotated through 180°. The hexacelsian crystallised at temperatures above 1100 °C as a disordered, metastable γ-hexacelsian (1H). A decrease in temperature leads to the ordering of O2 sites and the formation of partially ordered α-hexacelsian (2H), which preserves the disordered distribution of Al/Si at the tetrahedra. Some of the γ-hexacelsian grains in paralava were replaced by celsian under high-temperature conditions. Under low-temperature conditions, α-hexacelsian is replaced by cymrite during the zeolitisation of pyrometamorphic rocks of the Hatrurim Complex.
Known as a synthetic compound (disordered β-BaAl2Si2O8).
An analogue of synthetic low-temperature α-hexacelsian. The hexacelsian structure (polytype 2H) is formed by double layers of tetrahedra linked by their tops and bases, which are parallel to (001). Each layer is built from hexagonal (ditrigonal) rings of tetrahedra. The tetrahedra in rings with a disordered Al/Si distribution are rotated by approximately 14.5° compared to the position of the tetrahedra in ideal hexagonal rings in the high-temperature γ-hexacelsian. Every second layer in the structure of the studied hexacelsian is rotated through 180°. The hexacelsian crystallised at temperatures above 1100 °C as a disordered, metastable γ-hexacelsian (1H). A decrease in temperature leads to the ordering of O2 sites and the formation of partially ordered α-hexacelsian (2H), which preserves the disordered distribution of Al/Si at the tetrahedra. Some of the γ-hexacelsian grains in paralava were replaced by celsian under high-temperature conditions. Under low-temperature conditions, α-hexacelsian is replaced by cymrite during the zeolitisation of pyrometamorphic rocks of the Hatrurim Complex.
Unique Identifiers
Mindat ID:
46796
Long-form identifier:
mindat:1:1:46796:4
IMA Classification of Hexacelsian
Approved
Approval year:
2015
First published:
2017
Type description reference:
Galuskina, Irina O., Galuskin, Evgeny V., Vapnik, Yevgeny, Prusik, Krystian, Stasiak, Marta, Dzierżanowski, Piotr, Murashko, Mikhail (2017) Gurimite, Ba3(VO4)2 and hexacelsian, BaAl2Si2O8 – two new minerals from schorlomite-rich paralava of the Hatrurim Complex, Negev Desert, Israel. Mineralogical Magazine, 81 (4) 1009-1019 doi:10.1180/minmag.2016.080.147
Classification of Hexacelsian
9.FA.
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Hcls | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Hexacelsian
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Hexacelsian
Vitreous
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Hardness:
4½ - 6 on Mohs scale
Comment:
Strong anisotropy in hardness has been determined for hexacelsian, as measured on a plate crystal in a section perpendicular to (001). Along the plate, VHN25 = 492 (17) kg/mm2 (n = 14, range 453–519 kg/mm2) corresponds to a Mohs hardness of 4.5–5, while across the plane, VHN25 = 653 (21) (n = 12, range 616–694 kg/mm2) corresponds to a Mohs hardness of 5.5–6.
Cleavage:
Very Good
on (0001)
on (0001)
Fracture:
Irregular/Uneven
Density:
3.305 g/cm3 (Calculated)
Optical Data of Hexacelsian
Type:
Uniaxial
Pleochroism:
Non-pleochroic
Chemistry of Hexacelsian
Mindat Formula:
BaAl2Si2O8
Element Weights:
Elements listed:
Chemical Analysis
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Ba0.911K0.059Ca0.042Na0.010)Σ1.022Al1.891Fe3+0.072Si2.034O8 |
Sample references:
Crystallography of Hexacelsian
Crystal System:
Hexagonal
Class (H-M):
6/mmm(6/m2/m2/m) - Dihexagonal Dipyramidal
Space Group:
P63/mcm
Setting:
P63/mcm
Cell Parameters:
a = 5.2973(4) Å, c = 15.6068(10) Å
Ratio:
a:c = 1 : 2.946
Unit Cell V:
379.27 ų (Calculated from Unit Cell)
Comment:
Updated specimen from Mount Ye’elim
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) |
|---|---|---|---|---|---|---|---|
| 0013253 | Hexacelsian | Kremenovic A, Colomban P, Piriou B, Massiot D, Florian P (2003) Structural and spectroscopic characterization of the quenched hexacelsian Journal of Physics and Chemistry of Solids 64 2253-2268 | 2003 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.779 Å | (28) |
| 3.949 Å | (100) |
| 2.965 Å | (75) |
| 2.646 Å | (44) |
| 2.198 Å | (30) |
| 1.852 Å | (20) |
| 1.691 Å | (17) |
| 1.582 Å | (22) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
Type Occurrence of Hexacelsian
General Appearance of Type Material:
In oval polymineralic inclusions in paralava, as elongate crystals <10 μm thick
Place of Conservation of Type Material:
Type material is deposited in the collections of the Mineralogical Museum, University of Wrocław, Cybulskiego 30, 50-205 Wrocław, Poland, catalogue number MMUWr II-20465
Empirical Formula of Type Material:
(Ba0.911K0.059Ca0.042Na0.010)Σ1.022Al1.891Fe3+0.072Si2.034O8
Geological Setting of Type Material:
In veins of paralava cutting gehlenite-flamite hornfels located in the Gurim Anticline in the Negev Desert, Israel.
Associated Minerals at Type Locality:
Reference:
Galuskina, Irina O., Galuskin, Evgeny V., Vapnik, Yevgeny, Prusik, Krystian, Stasiak, Marta, Dzierżanowski, Piotr, Murashko, Mikhail (2017) Gurimite, Ba3(VO4)2 and hexacelsian, BaAl2Si2O8 – two new minerals from schorlomite-rich paralava of the Hatrurim Complex, Negev Desert, Israel. Mineralogical Magazine, 81 (4) 1009-1019 doi:10.1180/minmag.2016.080.147
Synonyms of Hexacelsian
Ba Feldspar (in part)
Other Language Names for Hexacelsian
German:Hexacelsian
Relationship of Hexacelsian to other Species
Member of:
Other Members of Feldspar Group:
| Alkali Feldspar | A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium. | |
| Buddingtonite | (NH4)(AlSi3O8) | Mon. 2 : P21 |
| Celsian | Ba(Al2Si2O8) | Mon. 2/m |
| Filatovite | K(Al,Zn)2(As,Si)2O8 | Mon. 2/m |
| Kokchetavite | K(AlSi3O8) | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Kumdykolite | Na(AlSi3O8) | Orth. mmm(2/m2/m2/m) : Pnnm |
| Paracelsian | Ba(Al2Si2O8) | Mon. 2/m : P21/b |
| Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 | |
| Reedmergnerite | NaBSi3O8 | Tric. 1 : P1 |
| Slawsonite | Sr(Al2Si2O8) | Mon. 2/m : P21/b |
| Svyatoslavite | Ca(Al2Si2O8) | Mon. 2 : P21 |
| 'Unnamed (New Ordered Member of the Alkali Feldspar Series)' | KNa(Si6Al2)O16 | Mon. m |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.FA. | Bonaccorsiite | KK2Na3(Al6Si36)O84 |
| 9.FA. | Wodegongjieite | KCa3(Al7Si9)O32 |
| 9.FA.05 | Panunzite | (K,Na)AlSiO4 |
| 9.FA.05 | Yoshiokaite | (Ca,Na)[Al(Al,Si)O4] |
| 9.FA.05 | Nepheline | Na3K(Al4Si4O16) |
| 9.FA.05 | Trinepheline | NaAlSiO4 |
| 9.FA.05 | Davidsmithite | (Ca,◻)2Na6Al8Si8O32 |
| 9.FA.05 | Kaliophilite | KAlSiO4 |
| 9.FA.05 | Kalsilite | KAlSiO4 |
| 9.FA.05 | 'Carnegieite' | NaAlSiO4 |
| 9.FA.05 | Megakalsilite | KAlSiO4 |
| 9.FA.05 | Trikalsilite | K2NaAl3(SiO4)3 |
| 9.FA.10 | Malinkoite | NaBSiO4 |
| 9.FA.15 | Virgilite | LiAlSi2O6 |
| 9.FA.25 | Lisitsynite | KBSi2O6 |
| 9.FA.30 | Ferrisanidine | K[Fe3+Si3O8] |
| 9.FA.30 | Buddingtonite | (NH4)(AlSi3O8) |
| 9.FA.30 | Rubicline | Rb(AlSi3O8) |
| 9.FA.30 | 'Monalbite' | NaAlSi3O8 |
| 9.FA.30 | Microcline | K(AlSi3O8) |
| 9.FA.30 va | 'Germanate-celsian' | BaAl2Ge2O8 |
| 9.FA.30 | Celsian | Ba(Al2Si2O8) |
| 9.FA.30 | Sanidine | K(AlSi3O8) |
| 9.FA.30 | Orthoclase | K(AlSi3O8) |
| 9.FA.35 | Reedmergnerite | NaBSi3O8 |
| 9.FA.35 | Albite | Na(AlSi3O8) |
| 9.FA.35 | Anorthite | Ca(Al2Si2O8) |
| 9.FA.40 | Paracelsian | Ba(Al2Si2O8) |
| 9.FA.45 | Svyatoslavite | Ca(Al2Si2O8) |
| 9.FA.45 | Kumdykolite | Na(AlSi3O8) |
| 9.FA.50 | Slawsonite | Sr(Al2Si2O8) |
| 9.FA.55 | Lisetite | CaNa2Al4Si4O16 |
| 9.FA.60 | Stronalsite | Na2SrAl4Si4O16 |
| 9.FA.60 | Banalsite | Na2BaAl4Si4O16 |
| 9.FA.65 | Maleevite | BaB2Si2O8 |
| 9.FA.65 | Pekovite | SrB2Si2O8 |
| 9.FA.65 | Danburite | CaB2Si2O8 |
| 9.FA.70 | Liebermannite | KAlSi3O8 |
| 9.FA.70 | Lingunite | NaAlSi3O8 |
| 9.FA.70 | Stöfflerite | CaAl2Si2O8 |
| 9.FA.75 | Pfaffenbergite | KNa3(Al4Si12)O32 |
| 9.FA.75 | Kokchetavite | K(AlSi3O8) |
Other Information
IR Spectrum:
Raman spectrum of hexacelsian is similar to the one of the synthetic disordered β-BaAl2Si2O8.
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 Hexacelsian
mindat.org URL:
https://www.mindat.org/min-46796.html
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References for Hexacelsian
Reference List:
Müller, W. F. (1976) On Polymorphism of BaAl2Si2O8. In Electron Microscopy in Mineralogy. Springer Berlin Heidelberg. p.354-360. doi:10.1007/978-3-642-66196-9_27
Hålenius, U.; Hatert, F.; Pasero, M.; Mills, S. J. (2015) New minerals and nomenclature modifications approved in 2015. Mineralogical Magazine, 79 (5). p.1223-1230. doi:10.1180/minmag.2015.079.5.16
Galuskina, Irina O., Galuskin, Evgeny V., Vapnik, Yevgeny, Prusik, Krystian, Stasiak, Marta, Dzierżanowski, Piotr, Murashko, Mikhail (2017) Gurimite, Ba3(VO4)2 and hexacelsian, BaAl2Si2O8 – two new minerals from schorlomite-rich paralava of the Hatrurim Complex, Negev Desert, Israel. Mineralogical Magazine, 81 (4) 1009-1019 doi:10.1180/minmag.2016.080.147
Localities for Hexacelsian
Showing 4 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.
Israel (TL) | |
| Galuskina et al. (2017) +1 other reference |
| Krzątała et al. (2023) | |
| Galuskin et al. (2026) | |
Palestine | |
| Galuskina et al. (2024) |
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Gurim anticline, Hatrurim Basin, Tamar Regional Council, Beersheba Subdistrict, Southern District, Israel