Hewettite Group
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About Hewettite Group
Formula:
MxV6O16 · nH2O
M denotes an alkali or alkaline earth cation, usually Na+ or Ca2+, and x is 1-1.5 for the naturally occurring members.
A group of monoclinic or orthorhombic vanadium-rich oxides (so-called vanadium bronzes). The structure consists of sheets with a chemical composition of (V6O16)n that are composed of laterally stacked alternating chains of (V2O6) and (V4O12) units. The open channels left between the sheets are occupied by the M ions and by water molecules. The average oxidation number of vanadium varies between 4.87 (grantsite) and 5.00 (barnesite and metahewettite). Thus, the compositions of some group members are seemingly non-stoichiometric (Evans and Hughes, 1990).
Several synthetic members of this group are known, e.g. Li3V6O16.
Several synthetic members of this group are known, e.g. Li3V6O16.
Unique Identifiers
Mindat ID:
40376
Long-form identifier:
mindat:1:1:40376:2
Chemistry of Hewettite Group
Mindat Formula:
MxV6O16 · nH2O
M denotes an alkali or alkaline earth cation, usually Na+ or Ca2+, and x is 1-1.5 for the naturally occurring members.
M denotes an alkali or alkaline earth cation, usually Na+ or Ca2+, and x is 1-1.5 for the naturally occurring members.
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) |
|---|---|---|---|---|---|---|---|
| 0005224 | Hewettite | Evans H T (1989) The crystal structure of hewettite The Canadian Mineralogist 27 181-188 |  | 1989 | Colorado Plateau, USA | 0 | 293 |
| 0005079 | Metahewettite | Bachmann H G, Barnes W H (1962) The crystal structure of a sodium-calcium variety of metahewettite The Canadian Mineralogist 7 219-235 | | 1962 | Paradox Valley, Montrose County, Coldrado,USA | 0 | 293 |
| 0005078 | Metahewettite | Bachmann H G, Barnes W H (1962) The crystal structure of a sodium-calcium variety of metahewettite The Canadian Mineralogist 7 219-235 | | 1962 | Paradox Valley, Montrose County, Coldrado,USA | 0 | 293 |
| 0018488 | Barnesite | Bachmann H G, Barnes W H (1962) The crystal structure of a sodium-calcium variety of metahewettite The Canadian Mineralogist 7 219-235 | | 1962 | Paradox Valley, Montrose County, Coldrado,USA | 0 | 293 |
CIF Raw Data - click here to close
Relationship of Hewettite Group to other Species
Hewettite Group Members:
| Barnesite | (Na,Ca)V6O16 · 3H2O | Mon. 2/m : P2/m |
| Grantsite | (Na,Ca)2+x(V5+,V4+)6O16 · 4H2O | Mon. 2/m : P21/m |
| Hendersonite | (Ca,Sr)1.3V6O16 · 6H2O | Orth. |
| Hewettite | CaV6O16 · 9H2O | Mon. 2/m : P21/m |
| Metahewettite | CaV6O16 · 3H2O | Mon. 2/m |
Click on any node to view relationships. Formula-derived relationship network for the group members above. Use Find related species to add formula-neighbour species outside the current group view. Solid links show inferred chemical differences; dashed violet links show same-formula crystallographic differences. Hydration states are not treated as relationship changes. These relationships do not imply any real-world substitution reactions between these species.
Minerals chemically related to group:
| Straczekite Group | Mx(V5+,V4+)8O20 · nH2O |
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 Hewettite Group
mindat.org URL:
https://www.mindat.org/min-40376.html
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References for Hewettite Group
Localities for Hewettite Group
Showing 182 localities.
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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.
Burro Mine, San Miguel County, Colorado, USA