Paracelsian
A valid IMA mineral species - grandfathered
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About Paracelsian
Formula:
Ba(Al2Si2O8)
Colour:
Colourless to white, light yellow tint.
Lustre:
Vitreous
Hardness:
6
Specific Gravity:
3.29 - 3.32
Crystal System:
Monoclinic
Member of:
Name:
From the Greek for "near" and "Celsian" in allusion to its relationship to that species.
Type Locality:
Polymorph of:
Feldspar Group. The pseudo-orthorhombic (the monoclinic angle is 90.01°) dimorph of Celsian.
Paracelsian appears to be a metastable phase; it changes monotropically through hexacelsian to celsian at temperatures at least as low as 500°C and possibly at lower temperatures also (Lin & Foster, 1968).
The morphology of the crystals makes them very similar to some chisel-shaped habits of topaz and danburite.
The paracelsian topology might invoke alternatively grouping - "paracelsian group" - also comprising danburite, pekovite, maleevite, hurlbutite and strontiohurlbutite.
Paracelsian appears to be a metastable phase; it changes monotropically through hexacelsian to celsian at temperatures at least as low as 500°C and possibly at lower temperatures also (Lin & Foster, 1968).
The morphology of the crystals makes them very similar to some chisel-shaped habits of topaz and danburite.
The paracelsian topology might invoke alternatively grouping - "paracelsian group" - also comprising danburite, pekovite, maleevite, hurlbutite and strontiohurlbutite.
Unique Identifiers
Mindat ID:
3082
Long-form identifier:
mindat:1:1:3082:9
GUID
(UUID V4):
(UUID V4):
61052bc2-21a3-49b6-85d1-d35a902ec561
IMA Classification of Paracelsian
Approved, 'Grandfathered' (first described prior to 1959)
Classification of Paracelsian
9.FA.40
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
76.1.5.1
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
16.12.5
16 : Silicates Containing Aluminum and other Metals
12 : Aluminosilicates of Sr, Ba and Zn
16 : Silicates Containing Aluminum and other Metals
12 : Aluminosilicates of Sr, Ba and Zn
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 |
---|---|---|
Pcls | 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 Paracelsian
Pronunciation:
Play | Recorded by | Country |
---|---|---|
Jolyon Ralph | United Kingdom |
Physical Properties of Paracelsian
Vitreous
Transparency:
Transparent, Translucent
Colour:
Colourless to white, light yellow tint.
Hardness:
6 on Mohs scale
Cleavage:
Poor/Indistinct
Poor cleavage {110} (unusual for feldspars).
Poor cleavage {110} (unusual for feldspars).
Fracture:
Sub-Conchoidal
Density:
3.29 - 3.32 g/cm3 (Measured) 3.342 g/cm3 (Calculated)
Optical Data of Paracelsian
Type:
Biaxial (-)
RI values:
nα = 1.570 nβ = 1.582 nγ = 1.587
2V:
Measured: 50° to 53°
Max Birefringence:
δ = 0.017
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:
Moderate
Dispersion:
r > v
Chemistry of Paracelsian
Mindat Formula:
Ba(Al2Si2O8)
Elements listed:
Common Impurities:
Fe,Mg,Ca,Na,K,H2O
Crystallography of Paracelsian
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 9.07 Å, b = 9.58 Å, c = 8.57 Å
β = 90.01°
β = 90.01°
Ratio:
a:b:c = 0.947 : 1 : 0.895
Unit Cell V:
744.65 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals prismatic, with {110} and {120} dominant, and with chisel-shaped terminations formed by {201}.
Twinning:
Twinning on {100}, simple; on {201}, lamellar.
Comment:
Pseudo-orthorhombic.
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) |
---|---|---|---|---|---|---|---|
0000997 | Paracelsian | Chiari G, Gazzoni G, Craig J R, Gibbs G V, Louisnathan S J (1985) Two independent refinements of the structure of paracelsian, BaAl2Si2O8 American Mineralogist 70 969-974 | 1985 | Benallt Mine, Carnarvonshire, U.K. | 0 | 293 | |
0000998 | Paracelsian | Chiari G, Gazzoni G, Craig J R, Gibbs G V, Louisnathan S J (1985) Two independent refinements of the structure of paracelsian, BaAl2Si2O8 American Mineralogist 70 969-974 | 1985 | Benallt Mine, Carnarvonshire, U.K. | 0 | 293 | |
0009156 | Paracelsian | Smith J V (1953) The crystal structure of paracelsian, BaAl2Si2O8 Acta Crystallographica 6 613-620 | 1953 | Benallt Mine, near Rhiw, Carnarvonshire, U.K. | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
4.00 Å | (100) |
3.80 Å | (70) |
2.99 Å | (50) |
2.73 Å | (50) |
2.56 Å | (50) |
3.59 Å | (45) |
2.37 Å | (45) |
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
High-𝑇 alteration and/or metamorphism | |
32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Paracelsian
General Appearance of Type Material:
Crystals prismatic, dominated by {110} and {120}, with chisel-shaped termination by {201}
Geological Setting of Type Material:
In a band through shales and sandstones, associated with a metamorphosed manganese deposit
Associated Minerals at Type Locality:
Reference:
Tacconi, E. (1905) Di un silicato di alluminio e bario [paracelsian] dei calcefiri di Candoglia in valle del Toce. Rend. R. Istit. Lombardo Sci. Lett., Milano, 38, 636-643 (in Italian).
Synonyms of Paracelsian
Ba Feldspar (in part)
Other Language Names for Paracelsian
Russian:Парацельзиан
Relationship of Paracelsian to other Species
Member of:
Other Members of this group:
Alkali Feldspar | A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium. | |
Banalsite | Na2BaAl4Si4O16 | Orth. mm2 : Iba2 |
Buddingtonite | (NH4)(AlSi3O8) | Mon. 2 : P21 |
Celsian | Ba(Al2Si2O8) | Mon. 2/m |
Cleavelandite | Na(AlSi3O8) | Tric. |
Filatovite | K(Al,Zn)2(As,Si)2O8 | Mon. 2/m |
Hexacelsian | BaAl2Si2O8 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mcm |
Kokchetavite | K(AlSi3O8) | Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc |
Kumdykolite | Na(AlSi3O8) | Orth. mmm (2/m 2/m 2/m) : Pnnm |
Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 | |
Reedmergnerite | NaBSi3O8 | Tric. 1 : P1 |
Slawsonite | Sr(Al2Si2O8) | Mon. 2/m : P21/b |
Stronalsite | Na2SrAl4Si4O16 | Orth. |
Svyatoslavite | Ca(Al2Si2O8) | Mon. 2 : P21 |
Unnamed (New Ordered Member of the Alkali Feldspar Series) | KNa(Si6Al2)O16 | Mon. m |
Related Minerals - Strunz-mindat Grouping
9.FA. | Hexacelsian | BaAl2Si2O8 |
9.FA. | Wodegongjieite | KCa3(Al7Si9)O32 |
9.FA.05 | Kaliophilite | KAlSiO4 |
9.FA.05 | Kalsilite | KAlSiO4 |
9.FA.05 | Nepheline | Na3K(Al4Si4O16) |
9.FA.05 | Panunzite | (K,Na)AlSiO4 |
9.FA.05 | Trikalsilite | K2NaAl3(SiO4)3 |
9.FA.05 | Yoshiokaite | (Ca,Na)[Al(Al,Si)O4] |
9.FA.05 | Carnegieite | NaAlSiO4 |
9.FA.05 va | Germanate-nepheline | (Na,K)AlGeO4 |
9.FA.05 | Megakalsilite | KAlSiO4 |
9.FA.05 | Trinepheline | NaAlSiO4 |
9.FA.05 | Davidsmithite | (Ca,◻)2Na6Al8Si8O32 |
9.FA.10 | Malinkoite | NaBSiO4 |
9.FA.15 | Virgilite | LiAlSi2O6 |
9.FA.25 | Lisitsynite | KBSi2O6 |
9.FA.30 | Buddingtonite | (NH4)(AlSi3O8) |
9.FA.30 | Celsian | Ba(Al2Si2O8) |
9.FA.30 | Microcline | K(AlSi3O8) |
9.FA.30 | Orthoclase | K(AlSi3O8) |
9.FA.30 | Sanidine | K(AlSi3O8) |
9.FA.30 | Rubicline | Rb(AlSi3O8) |
9.FA.30 va | Germanate-celsian | BaAl2Ge2O8 |
9.FA.30 | Monalbite | NaAlSi3O8 |
9.FA.30 | Ferrisanidine | K[Fe3+Si3O8] |
9.FA.35 | Albite | Na(AlSi3O8) |
9.FA.35 | Anorthite | Ca(Al2Si2O8) |
9.FA.35 | Reedmergnerite | NaBSi3O8 |
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 | Banalsite | Na2BaAl4Si4O16 |
9.FA.60 | Stronalsite | Na2SrAl4Si4O16 |
9.FA.65 | Danburite | CaB2Si2O8 |
9.FA.65 | Maleevite | BaB2Si2O8 |
9.FA.65 | Pekovite | SrB2Si2O8 |
9.FA.70 | Stöfflerite | CaAl2Si2O8 |
9.FA.70 | Lingunite | (Na,Ca)AlSi3O8 |
9.FA.70 | Liebermannite | KAlSi3O8 |
9.FA.75 | Kokchetavite | K(AlSi3O8) |
Other Information
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 Paracelsian
mindat.org URL:
https://www.mindat.org/min-3082.html
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References for Paracelsian
Reference List:
Chiari, G., Gazzoni, G., Craig, J. R., Gibbs, G. V., Louisnathan, S. J. (1985) Two independent refinements of the structure of paracelsian, BaAl2Si2O8. American Mineralogist, 70 (9-10) 969-974
Cressey, G. (2004) W.A. Deer, R.A. Howie, W.S. Wise and J. Zussman. Rock-Forming Minerals. Volume 4B. Second Edition. Framework Silicates: Silica Minerals, Feldspathoids and the Zeolites.
London (The Geological Society) 2004, xv + 982 pp. £125 (£62.50 to GSL members) ISBN 1-86239-144-0. Hardback. Mineralogical Magazine, 68 (5) 831-832 doi:10.1180/0680831pp.166-178
Localities for Paracelsian
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.
Italy (TL) | |
| Tacconi (1905) |
Romania | |
| minerals-of-the-carpathians.eu (2008) |
UK | |
| Spencer (1942) +1 other reference |
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Benallt Mine, Rhiw, Aberdaron, Gwynedd, Wales, UK