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Giuseppettite
A valid IMA mineral species
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About Giuseppettite
Formula:
(Na,K,Ca)7-8(Al6Si6O24)(SO4,Cl)1-2
Colour:
Pale purple
Hardness:
6 - 7
Specific Gravity:
2.35
Crystal System:
Trigonal
Member of:
Name:
For Giuseppe Giuseppetti, Professor of Mineralogy, University of Pavia, Pavia, Italy.
Unique Identifiers
Mindat ID:
1703
Long-form identifier:
mindat:1:1:1703:5
IMA Classification of Giuseppettite
Approved
IMA Formula:
Na42K16Ca6Si48Al48O192(S6+O4)10Cl2·5H2O
Approval year:
1979
First published:
1981
Classification of Giuseppettite
9.FB.05
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
76.2.5.7
76 : TECTOSILICATES Al-Si Framework
2 : Al-Si Framework Feldspathoids and related species
76 : TECTOSILICATES Al-Si Framework
2 : Al-Si Framework Feldspathoids and related species
17.10.14
17 : Silicates Containing other Anions
10 : Silicates with sulphate, molybdate or tungstate
17 : Silicates Containing other Anions
10 : Silicates with sulphate, molybdate or tungstate
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 |
|---|---|---|
| Giu | 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 Giuseppettite
Transparency:
Transparent
Colour:
Pale purple
Streak:
White
Hardness:
6 - 7 on Mohs scale
Cleavage:
None Observed
Density:
2.35 g/cm3 (Measured) 2.32 g/cm3 (Calculated)
Optical Data of Giuseppettite
Type:
Uniaxial (+)
RI values:
nω = 1.491 nε = 1.507
Max. Birefringence:
δ = 0.016
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 (negative)
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 Giuseppettite
Mindat Formula:
(Na,K,Ca)7-8(Al6Si6O24)(SO4,Cl)1-2
Element Weights:
Common Impurities:
Fe
Crystallography of Giuseppettite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
P31c
Cell Parameters:
a = 12.856(2) Å, c = 42.256(8) Å
Ratio:
a:c = 1 : 3.287
Unit Cell V:
6,048.26 ų (Calculated from Unit Cell)
Z:
1
Twinning:
Twinned on (001)
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) |
|---|---|---|---|---|---|---|---|
| 0014409 | Giuseppettite | Bonaccorsi E (2004) The crystal structure of giuseppettite, the 16-layer member of the cancrinite- sodalite group Microporous and Mesoporous Materials 73 129-136 | 2004 | Sacrofano, Biachella Valley, Latium, Italy | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.712 Å | (100) |
| 3.446 Å | (80) |
| 3.126 Å | (70) |
| 2.141 Å | (66) |
| 6.42 Å | (62) |
| 2.640 Å | (62) |
| 4.318 Å | (53) |
Comments:
Sacrofano, Italy. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Giuseppettite
General Appearance of Type Material:
Anhedral grains, in veinlets a few mm thick.
Place of Conservation of Type Material:
University of Pavia, Pavia, and Mineralogical Museum, University of Rome (#24341), Italy.
Geological Setting of Type Material:
Sanidinite volcanic ejecta.
Associated Minerals at Type Locality:
Synonyms of Giuseppettite
Other Language Names for Giuseppettite
Dutch:Giuseppettiet
German:Giuseppettit
Simplified Chinese:久硅铝钠石
Spanish:Giuseppettita
Traditional Chinese:久矽鋁鈉石
Relationship of Giuseppettite to other Species
Member of:
Other Members of Cancrinite Group:
| Afghanite | (Na,K)22Ca10(Si24Al24O96)(SO4)6Cl6 | Trig. 3m : P31c |
Sacrofano, Metropolitan City of Rome Capital, Lazio, Italy