Demagistrisite
A valid IMA mineral species
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About Demagistrisite
Formula:
BaCa2Mn3+4(Si3O10)(Si2O7)(OH)4 · 3H2O
Colour:
orange brown to red brown
Lustre:
Vitreous
Crystal System:
Orthorhombic
Name:
Named in honor of Leandro De Magistris (1906-1990), former honorary curator of the Genova Mineralogical Museum.
New structure type. Chemically somewhat related to various mineral species, e.g., the unapproved 'bariumbannisterite' or muirite. Described as "the missing link in a polysomatic series from lawsonite to orientite".
Crystal structure (intermediate between that of orientite and noelbensonite) details:
- straight edge-sharing chains of Mn3+-centred octahedra, running along [010],
- they are bridged by disilicate and trisilicate groups;
- cavities within thus formed framework bear two large cation sites.
Crystal structure (intermediate between that of orientite and noelbensonite) details:
- straight edge-sharing chains of Mn3+-centred octahedra, running along [010],
- they are bridged by disilicate and trisilicate groups;
- cavities within thus formed framework bear two large cation sites.
Unique Identifiers
Mindat ID:
53156
Long-form identifier:
mindat:1:1:53156:0
IMA Classification of Demagistrisite
Approved
IMA Formula:
BaCa2Mn3+4(Si3O10)(Si2O7)(OH)4·3H2O
Approval year:
2018
First published:
2021
Type description reference:
Classification of Demagistrisite
9.HA.35
9 : SILICATES (Germanates)
H : Unclassified silicates
A : With Alkali and Alkali-earth Elements
9 : SILICATES (Germanates)
H : Unclassified silicates
A : With Alkali and Alkali-earth Elements
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 |
|---|---|---|
| Dmg | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Demagistrisite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Orange brown to red brown
Comment:
orange brown in thin section
Streak:
Beige
Fracture:
Irregular/Uneven
Optical Data of Demagistrisite
Type:
Biaxial (-)
RI values:
nα = 1.805(5) nβ = 1.825(5) nγ = 1.8305(5)
2V:
Measured: 58° (5), Calculated: 54.7°
Max. Birefringence:
δ = 0.026
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
Dispersion:
very strong, r > v
Pleochroism:
Strong
Comments:
X - orange yellow, Y - red brown, Z - red brown; X << Z < Y
Comments:
optical orientation: X = c, Y = b, Z = a
Chemistry of Demagistrisite
Mindat Formula:
BaCa2Mn3+4(Si3O10)(Si2O7)(OH)4 · 3H2O
Element Weights:
Crystallography of Demagistrisite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Amm2
Cell Parameters:
a = 16.3160(6) Å, b = 6.1830(2) Å, c = 9.0740(3) Å
Ratio:
a:b:c = 2.639 : 1 : 1.468
Unit Cell V:
915.40 ų (Calculated from Unit Cell)
Morphology:
Needles with square cross-section, typically with irregular terminations, and rarely terminated by a low-angle pyramid.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 16.21 Å | (49) |
| 4.86 Å | (44) |
| 4.34 Å | (56) |
| 3.196 Å | (43) |
| 2.871 Å | (54) |
| 2.731 Å | (100) |
| 2.671 Å | (74) |
| 2.426 Å | (51) |
Reference:
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Demagistrisite
General Appearance of Type Material:
(1) tightly intergrown blades, (2) mm-sized prisms & needles with square cross section, often having irregular terminations, rarely terminated by a low-angle pyramid
Place of Conservation of Type Material:
Type material is deposited in the mineralogical collections of the Museum of the Earth Sciences Department, Università di Milano, Via Mangiagalli 34, 20133 Milano, Italy, registration number MCMGPG-H2018-004 (holotype), and the Natural History Museum of Los Angeles County, registration numbers 66942 and 66943 (cotype).
Geological Setting of Type Material:
Mn ore within cherts; the matrix bears braunite, calcite, cryptomelane, orthoclase, and quartz
Associated Minerals at Type Locality:
Synonyms of Demagistrisite
Other Language Names for Demagistrisite
Dutch:Demagistrisiet
German:Demagistrisit
Related Minerals - Strunz-mindat Grouping
| 9.HA. | Shinichengite | Ca5[BSi2O7(OH)2]2 · 6H2O |
| 9.HA. | Kalyuzhnyite-(Ce) | NaKCaSrCeTi(Si8O21)OF(H2O)3 |
| 9.HA. | Moragite | Ca3TiSi2(Al2Si)O14 |
| 9.HA.05 | Ertixiite | Na2Si4O9 |
| 9.HA.10 | Kenyaite | Na2Si22O41(OH)8 · 6H2O |
| 9.HA.20 | Wawayandaite | Ca6Mn2BBe9Si6O23(OH,Cl)15 |
| 9.HA.25 | Magbasite | KBaFe3+Mg7Si8O22(OH)2F6 |
| 9.HA.37 | Donwilhelmsite | CaAl4Si2O11 |
| 9.HA.40 | Kasatkinite | Ba2Ca8B5Si8O32(OH)3 · 6H2O |
| 9.HA.40 | 'Igumnovite' | Ca3Al2[SiO4]2[◻Cl4] |
| 9.HA.42 | Paqueite | Ca3TiSi2(Al,Ti,Si)3O14 |
| 9.HA.42 | Qeltite | Ca3TiSi2(Fe3+2Si)O14 |
| 9.HA.45 | Rippite | K2(Nb,Ti)2(Si4O12)O(O,F) |
| 9.HA.47 | Zagamiite | CaAl2Si3.5O11 |
| 9.HA.50 | Rudenkoite | Sr3(Al3.5Si3.5)O10(OH,O)8Cl2 · H2O |
| 9.HA.50 | 'α-Carnegieite' | NaAlSiO4 |
| 9.HA.52 | 'Atheriastite' | near Ca5MgFeAl6Si8O32 · 5H2O |
| 9.HA.55 | 'Foshallasite' | Ca3[Si2O7] · 3H2O(?) |
| 9.HA.57 | 'Bhreckite' | |
| 9.HA.60 | Nagelschmidtite | Ca7(SiO4)2(PO4)2 |
| 9.HA.65 | Caryochroite | [Na(Sr0.5Ca0.5)Mg]3[Fe3+8Mn(Fe2+0.5◻0.5)]10(Ti2Si12O37)(OH)14(H2O)3 |
| 9.HA.70 | Juanite | Ca10Mg4Al2Si11O39 · 4H2O or near |
| 9.HA.75 | Tacharanite | Ca12Al2Si18O33(OH)36 |
| 9.HA.80 | Oyelite | Ca10Si8B2O29 · 12.5H2O |
| 9.HA.85 | Denisovite | K14+x(Ca,Na,Mn,Fe)48[Si60O162]F16(Ox,OH4-x) · 2H2O |
| 9.HA.90 | Tiettaite | K4Na12Fe3+Si16O41(OH)4 · 2H2O |
Other Information
Notes:
Does not react with HCl at room temperature
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 Demagistrisite
mindat.org URL:
https://www.mindat.org/min-53156.html
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Please feel free to link to this page.
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References for Demagistrisite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2018) CNMNC Newsletter 45, New minerals and nomenclature modifications approved in 2018. Mineralogical Magazine, 82 (5) 1225-1232 doi:10.1180/mgm.2018.160p.1229
Localities for Demagistrisite
Showing 1 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.
Italy (TL) | |
| Hålenius et al. (2018) +1 other reference |
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Cerchiara Mine, Borghetto di Vara, La Spezia Province, Liguria, Italy