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Grumantite
A valid IMA mineral species
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About Grumantite
Grumant
Formula:
Na(HSi2O5) · H2O
Colour:
white
Lustre:
Vitreous, Silky, Dull
Hardness:
4 - 5
Specific Gravity:
2.21
Crystal System:
Orthorhombic
Name:
From an old Russian name for the Spitzbergen Archipelago.
This page provides mineralogical data about Grumantite.
Unique Identifiers
Mindat ID:
1757
Long-form identifier:
mindat:1:1:1757:8
IMA Classification of Grumantite
Approved
IMA Formula:
NaSi2O4(OH)·H2O
Approval year:
1985
First published:
1987
Classification of Grumantite
9.EH.10
9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units
9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units
78.4.5.1
78 : Unclassified Silicates
4 :
78 : Unclassified Silicates
4 :
14.1.7
14 : Silicates not Containing Aluminum
1 : Silicates of the alkali metals
14 : Silicates not Containing Aluminum
1 : Silicates of the alkali metals
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 |
|---|---|---|
| Gmt | 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 Grumantite
Vitreous, Silky, Dull
Transparency:
Transparent
Comment:
Aggregates dull to silky, single crystals vitreous
Colour:
White
Streak:
White
Hardness:
4 - 5 on Mohs scale
Hardness Data:
Measured
Cleavage:
Perfect
on {100}
on {100}
Fracture:
Step-Like
Density:
2.21 g/cm3 (Measured) 2.26 g/cm3 (Calculated)
Optical Data of Grumantite
Type:
Biaxial (+)
RI values:
nα = 1.494(2) nβ = 1.507(2) nγ = 1.523(2)
2V:
Measured: 83° to 87°, Calculated: 84.9°
Max. Birefringence:
δ = 0.029
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:
weak, r > v
Optical Extinction:
X = a, Y = c, Z = b
Chemistry of Grumantite
Mindat Formula:
Na(HSi2O5) · H2O
Element Weights:
Elements listed:
Crystallography of Grumantite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Fdd2
Cell Parameters:
a = 15.979 Å, b = 18.25 Å, c = 7.169 Å
Ratio:
a:b:c = 0.876 : 1 : 0.393
Unit Cell V:
2,090.60 ų (Calculated from Unit Cell)
Z:
16
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.505 Å | (100) |
| 3.006 Å | (100) |
| 6.20 Å | (50) |
| 6.05 Å | (50) |
| 4.46 Å | (50) |
| 3.087 Å | (50) |
| 3.346 Å | (25) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Grumantite
General Appearance of Type Material:
irregular crystals, compact massive
Place of Conservation of Type Material:
Geology Museum, Kola Branch, Academy of Sciences, Apatity, Russia.
Mineralogical Museum, St. Petersberg, Russia.
A.E.Fersman Mineralogical Museum, Moscow, Russia.
Mineralogical Museum, St. Petersberg, Russia.
A.E.Fersman Mineralogical Museum, Moscow, Russia.
Geological Setting of Type Material:
in veins cutting alkalic feldspathoid-bearing pegmatites in a differentiated alkalic massif
Associated Minerals at Type Locality:
Synonyms of Grumantite
Other Language Names for Grumantite
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.EH.05 | Manganoneptunite | KNa2Li(Mn2+)2Ti2[Si4O12]2 |
| 9.EH.05 | Magnesioneptunite | KNa2Li(Mg)2Ti2[Si4O12]2 |
| 9.EH.05 | Neptunite | KNa2Li(Fe2+)2Ti2[Si4O12]2 |
| 9.EH.05 | Watatsumiite | KNa2Li(Mn2+)2V4+2[Si4O12]2 |
| 9.EH.05 | Rotherkopfite | KNa2Fe2+(Fe2+)2(Ti1.5Fe2+0.5)[Si4O12]2 |
| 9.EH.15 | Sarcolite | Na4Ca12Al8Si12O46(SiO4,PO4)(OH,H2O)4(CO3,Cl) |
| 9.EH.20 | Ussingite | Na2AlSi3O8OH |
| 9.EH.25 | Telyushenkoite | (Cs,Na,K)Na6[Be2Al3Si15O39]F2 |
| 9.EH.25 | Leifite | (Na,H2O)Na6[Be2Al2(Al,Si)Si15O39]F2 |
| 9.EH.25 | Eirikite | KNa6Be2(Si15Al3)O39F2 |
| 9.EH.30 | Nafertisite | Na3Fe2+10Ti2(Si6O17)2O2(OH)6F(H2O)2 |
| 9.EH.35 | Veblenite | KNa(Fe2+5Fe3+4Mn7)Nb4(Si2O7)2(Si8O22)2O6(OH)10(H2O)3 |
Fluorescence of Grumantite
Weak, bluish white
Other Information
Thermal Behaviour:
The DTA curve exhibits marked endothermal effects at 280°C (dehydration), 700°C (phase transition), and 760°C (melting).
Notes:
Insoluble in cold water and cold 10% HCl, readily
soluble in hot 10% HCl giving a silicic residue.
soluble in hot 10% HCl giving a silicic residue.
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 Grumantite
mindat.org URL:
https://www.mindat.org/min-1757.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
Alluaiv Mountain, Lovozersky District, Murmansk Oblast, Russia