Tvedalite
A valid IMA mineral species
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About Tvedalite
Formula:
(Ca,Mn)4Be3Si6O17(OH)4 · 3H2O
Colour:
Creamy-white, light beige
Lustre:
Vitreous
Hardness:
4½
Specific Gravity:
2.541
Crystal System:
Orthorhombic
Name:
Named after its discovery locality, Vevja quarry, Tvedalen area, Vestfold, Norway.
Type Locality:
Unique Identifiers
Mindat ID:
4065
Long-form identifier:
mindat:1:1:4065:1
IMA Classification of Tvedalite
Approved
IMA Formula:
Ca4Be3Si6O17(OH)4·3H2O
Approval year:
1990
First published:
1992
Classification of Tvedalite
9.DF.20
9 : SILICATES (Germanates)
D : Inosilicates
F : Inosilicates with 2-periodic multiple chains
9 : SILICATES (Germanates)
D : Inosilicates
F : Inosilicates with 2-periodic multiple chains
70.5.2.1
70 : INOSILICATES Column or Tube Structures
5 : Column or Tube Structures with chains linked by Be
70 : INOSILICATES Column or Tube Structures
5 : Column or Tube Structures with chains linked by Be
14.3.19
14 : Silicates not Containing Aluminum
3 : Silicates of Be
14 : Silicates not Containing Aluminum
3 : Silicates of Be
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 |
|---|---|---|
| Tve | 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 Tvedalite
Vitreous
Transparency:
Translucent
Colour:
Creamy-white, light beige
Streak:
White
Hardness:
4½ on Mohs scale
Hardness Data:
Estimated
Cleavage:
Perfect
{010}
{010}
Density:
2.541 g/cm3 (Measured) 2.554 g/cm3 (Calculated)
Optical Data of Tvedalite
Type:
Biaxial
Dispersion:
r > v
Chemistry of Tvedalite
Mindat Formula:
(Ca,Mn)4Be3Si6O17(OH)4 · 3H2O
Element Weights:
Common Impurities:
Al,Fe
Crystallography of Tvedalite
Crystal System:
Orthorhombic
Cell Parameters:
a = 8.72 Å, b = 23.14 Å, c = 4.92 Å
Ratio:
a:b:c = 0.377 : 1 : 0.213
Unit Cell V:
992.76 ų (Calculated from Unit Cell)
Comment:
C-centered lattice, space group unknown
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.6 Å | (93) |
| 5.80 Å | (68) |
| 3.87 Å | (75) |
| 3.16 Å | (74) |
| 2.889 Å | (75) |
| 2.837 Å | (100) |
| 2.494 Å | (58) |
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 Tvedalite
General Appearance of Type Material:
Spherulites up to 3 mm in diameter composed of densely packed, radially oriented platelets (a few μm in length). The spherulites are overgrown by a crust of chiavennite.
Place of Conservation of Type Material:
University of Oslo, Oslo, Norway, 14770.
Geological Setting of Type Material:
In heavily zeolitized and hydrothermally parts of irregular nepheline syenite pegmatites.
Associated Minerals at Type Locality:
Synonyms of Tvedalite
Other Language Names for Tvedalite
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.DF. | Bohseite | Ca4Be3+xAl1-xSi9O25-x(OH)3+x |
| 9.DF.05 | Jimthompsonite | (Mg,Fe)5Si6O16(OH)2 |
| 9.DF.05 | Clinojimthompsonite | (Mg,Fe)5Si6O16(OH)2 |
| 9.DF.05 | Chesterite | (Mg,Fe)17Si20O54(OH)6 |
| 9.DF.15 | Ershovite | Na4K3(Fe,Mn,Ti)2Si8O22(OH)4 · 4H2O |
| 9.DF.15 | Paraershovite | Na3K3Fe3+2Si8O20(OH)4 · 4H2O |
| 9.DF.25 | Bavenite | Ca4Be2Al2Si9O26(OH)2 |
| 9.DF.30 | Bigcreekite | BaSi2O5 · 4H2O |
Fluorescence of Tvedalite
non-fluorescent
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 Tvedalite
mindat.org URL:
https://www.mindat.org/min-4065.html
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Please feel free to link to this page.
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References for Tvedalite
Localities for Tvedalite
Showing 7 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.
Norway | |
| Larsen et al. (2005) |
| Nordrum (2002) +1 other reference |
| Nordrum (2004) +1 other reference | |
| Grice et al. (2013) |
| Larsen et al. (1992) +2 other references |
Spain | |
| Dill et al. (2023) |
| Dill et al. (2023) |
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Vevja Quarry, Tvedalen, Larvik Commune, Vestfold, Norway