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Dickthomssenite
A valid IMA mineral species
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About Dickthomssenite
Dick W. Thomssen
Formula:
Mg(V2O6) · 7H2O
Colour:
Light golden brown
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
1.96 - 2.09
Crystal System:
Monoclinic
Name:
In honor of Richard ("Dick") W. Thomssen [b. April 23, 1933 USA], consulting geologist, Dayton, Nevada, USA.
This page provides mineralogical data about Dickthomssenite.
Unique Identifiers
Mindat ID:
11216
Long-form identifier:
mindat:1:1:11216:1
IMA Classification of Dickthomssenite
Classification of Dickthomssenite
4.HD.25
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
D : Inovanadates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
D : Inovanadates
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 |
|---|---|---|
| Dth | 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 Dickthomssenite
Vitreous
Transparency:
Translucent
Colour:
Light golden brown
Streak:
White
Hardness:
2½ on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Perfect
{100}
{100}
Fracture:
Hackly
Density:
1.96 - 2.09 g/cm3 (Measured) 2.04 g/cm3 (Calculated)
Optical Data of Dickthomssenite
Type:
Biaxial (-)
RI values:
nα = 1.6124 nβ = 1.674 nγ = 1.7104
2V:
Measured: 74° , Calculated: 73°
Max. Birefringence:
δ = 0.098
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:
Very High (positive)
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v
Optical Extinction:
Z = b; Y ∧ c = 17°.
Pleochroism:
Non-pleochroic
Chemistry of Dickthomssenite
Mindat Formula:
Mg(V2O6) · 7H2O
Element Weights:
Elements listed:
Crystallography of Dickthomssenite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 38.954 Å, b = 7.201 Å, c = 16.3465 Å
β = 97.602°
β = 97.602°
Ratio:
a:b:c = 5.41 : 1 : 2.27
Unit Cell V:
4544 ų
Z:
16
Twinning:
None mentioned
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.704 Å | (100) |
| 8.117 Å | (60) |
| 5.843 Å | (100) |
| 4.061 Å | (50) |
| 3.139 Å | (90) |
| 2.920 Å | (60) |
| 2.707 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47e : [Vanadates, chromates, manganates] |
Type Occurrence of Dickthomssenite
General Appearance of Type Material:
Crystals ranging from 0.25-mm needle-like to 0.5 x 1.5 mm platy, prismatic crystals with basal terminations. The crystals occur in fibroradial groups to a length of 5 mm, creating solid coverage to 1.5 x 2.5 cm.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA.
Geological Setting of Type Material:
Coating on sandstone.
Associated Minerals at Type Locality:
Synonyms of Dickthomssenite
Other Language Names for Dickthomssenite
Dutch:Dickthomsseniet
German:Dickthomssenit
Russian:Диктомссенит
Simplified Chinese:水镁钒石
Spanish:Dickthomssenita
Traditional Chinese:水鎂釩石
Common Associates
Associations Based on Photo Data:
| 8 photos of Dickthomssenite associated with Lasalite | Na2Mg2(V10O28) · 20H2O |
| 6 photos of Dickthomssenite associated with Metarossite | Ca(V2O6) · 2H2O |
| 4 photos of Dickthomssenite associated with Native Selenium | Se |
| 2 photos of Dickthomssenite associated with Rossite | Ca(VO3)2 · 4H2O |
| 2 photos of Dickthomssenite associated with Hewettite | CaV6O16 · 9H2O |
| 2 photos of Dickthomssenite associated with Simplotite | CaV4+4O9 · 5H2O |
| 1 photo of Dickthomssenite associated with Trebiskyite | Na3Mg2[TiV9O28] · 22H2O |
Related Minerals - Strunz-mindat Grouping
| 4.HD. | Pseudodickthomssenite | Mg(VO3)2 · 8H2O |
| 4.HD.05 | Rossite | Ca(VO3)2 · 4H2O |
| 4.HD.10 | Metarossite | Ca(V2O6) · 2H2O |
| 4.HD.15 | Munirite | NaVO3 · 1.9H2O |
| 4.HD.20 | Metamunirite | NaVO3 |
| 4.HD.30 | Ansermetite | Mn2+(V2O6) · 4H2O |
Fluorescence of Dickthomssenite
Not 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 Dickthomssenite
mindat.org URL:
https://www.mindat.org/min-11216.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Dickthomssenite
Reference List:
Hughes, J. M., Cureton, F. E., Marty, J., Gault, R. A., Gunter, M. E., Campana, C. F., Rakovan, J., Sommer, A., Brueseke, M. E. (2001) Dickthomssenite, Mg(V2O6)·7H2O, a new mineral species from the Firefly-Pigmay Mine, Utah: descriptive mineralogy and arrangement of atoms. The Canadian Mineralogist, 39 (6) 1691-1700 doi:10.2113/gscanmin.39.6.1691
Localities for Dickthomssenite
Showing 8 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.
USA | |
| Kampf et al. (2017) |
| Travis Olds collection |
| Carnegie Museum of Natural History ... | |
| Kasatkin et al. (2014) +1 other reference |
| Chuck Adan specimen. Analyzed by Tony ... | |
| EDX results from Kaygeedee Minerals +1 other reference |
| Hughes et al. (2001) |
| Hughes et al. (2008) |
Quick NavTopAbout DickthomsseniteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Blue Streak Mine, Montrose County, Colorado, USA