Hewettite
A valid IMA mineral species - grandfathered
This page kindly sponsored by Jeff Weissman
About Hewettite
D. Foster Hewett
Formula:
CaV6O16 · 9H2O
Colour:
Deep red; chocolate brown (upon exposure); red to orange in transmitted light
Lustre:
Adamantine, Silky
Specific Gravity:
2.51 - 2.61
Crystal System:
Monoclinic
Member of:
Name:
Named in honor of Donnel Foster Hewett (June 24, 1881, Irwin, Pennsylvania - February 5, 1971), U.S. Geological Survey, who studied the mineralogy of Mina Ragra, Cerro de Pasco, Peru. He was primarily responsible for the discovery of that, the largest vanadium deposit in the world.
Type Locality:
A secondary mineral resulting from the alteration of patronite (TL), or from the alteration of less-oxidized vanadium minerals.
May reversibly dehydrate to metahewettite.
May reversibly dehydrate to metahewettite.
Unique Identifiers
Mindat ID:
1890
Long-form identifier:
mindat:1:1:1890:2
IMA Classification of Hewettite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaV5+6O16 · 9H2O
First published:
1914
Classification of Hewettite
4.HE.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
E : Phyllovanadates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
E : Phyllovanadates
47.3.1.1
47 : VANADIUM OXYSALTS
3 : Hydrated Normal Vanadium Oxysalts
47 : VANADIUM OXYSALTS
3 : Hydrated Normal Vanadium Oxysalts
21.2.4
21 : Vanadates (and vanadates with arsenate or phosphate)
2 : Vanadates of Mg, Ca, Sr or Ba
21 : Vanadates (and vanadates with arsenate or phosphate)
2 : Vanadates of Mg, Ca, Sr or Ba
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 |
|---|---|---|
| Hew | 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 Hewettite
Adamantine, Silky
Transparency:
Transparent
Colour:
Deep red; chocolate brown (upon exposure); red to orange in transmitted light
Comment:
Extremely soft.
Density:
2.51 - 2.61 g/cm3 (Measured) 2.67 g/cm3 (Calculated)
Optical Data of Hewettite
Type:
Biaxial (-)
RI values:
nα = 1.770 nβ = 2.180 nγ = 2.350 - 2.400
Max. Birefringence:
δ = 0.580 - 0.630
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.
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.
Surface Relief:
Moderate
Dispersion:
r > v distinct
Optical Extinction:
Parallel. Z = c.
Pleochroism:
Visible
Comments:
X = Y = Light yellow-orange; Z = Dark red.
Comments:
2V medium
Chemistry of Hewettite
Mindat Formula:
CaV6O16 · 9H2O
Element Weights:
Elements listed:
Crystallography of Hewettite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Cell Parameters:
a = 12.29 Å, b = 3.59 Å, c = 11.174 Å
β = 97.24°
β = 97.24°
Ratio:
a:b:c = 3.423 : 1 : 3.113
Unit Cell V:
489.08 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Crystals acicular and as fibers, elongated and intertwined parallel [010]; nodular aggregates, fracture fillings, and coatings.
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 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.03 Å | (100) |
| 5.63 Å | (12) |
| 5.53 Å | (35) |
| 3.660 Å | (14) |
| 3.091 Å | (20) |
| 2.574 Å | (12) |
| 2.164 Å | (25) |
Comments:
Monument No. 2 mine, Arizona, USA. The data are from Bayliss (1982).
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] |
Geological Setting:
Colorado Plateau-type U-V deposits
Type Occurrence of Hewettite
General Appearance of Type Material:
Lumpy aggregates, composed of needles usually less than 0.01 x 0.2 mm.
Place of Conservation of Type Material:
U.S. National Museum of Natural History, Washington, D.C., USA: #87459.
Geological Setting of Type Material:
Very rich vanadium deposit in sedimentary rocks.
Associated Minerals at Type Locality:
Other Language Names for Hewettite
Relationship of Hewettite to other Species
Member of:
Other Members of Hewettite Group:
| 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. |
| Metahewettite | CaV6O16 · 3H2O | Mon. 2/m |
Common Associates
Associated Minerals Based on Photo Data:
| 23 photos of Hewettite associated with Opal | SiO2 · nH2O |
| 23 photos of Hewettite associated with Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
| 17 photos of Hewettite associated with Gypsum | CaSO4 · 2H2O |
| 12 photos of Hewettite associated with Kazakhstanite | Fe3+5V4+3V5+12O39(OH)9 · 9H2O |
| 11 photos of Hewettite associated with Fluellite | Al2(PO4)F2(OH) · 7H2O |
| 11 photos of Hewettite associated with Variscite | AlPO4 · 2H2O |
| 9 photos of Hewettite associated with Nevadaite | (Cu2+,Al,V3+)6Al8(PO4)8F8(OH)2 · 22H2O |
| 9 photos of Hewettite associated with Baryte | BaSO4 |
| 8 photos of Hewettite associated with Rauvite | Ca(UO2)2(V10O28) · 16H2O |
| 7 photos of Hewettite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
| 4.HE.05 | Melanovanadite | Ca(V5+,V4+)4O10 · 5H2O |
| 4.HE.10 | Shcherbinaite | V5+2O5 |
| 4.HE.15 | Metahewettite | CaV6O16 · 3H2O |
| 4.HE.20 | Bariandite | Al0.6(V5+,V4+)8O20 · 9H2O |
| 4.HE.20 | Corvusite | (Na,K,Ca,Mg)2(V5+,V4+,Fe2+)8O20 · 6-10H2O |
| 4.HE.20 | Bokite | (Al,Fe)1.3(V5+,V4+,Fe3+)8O20 · 7.5H2O |
| 4.HE.20 | Fernandinite | (Ca,K)(V5+,V4+,Fe2+)8O20 · 10H2O |
| 4.HE.20 | Straczekite | (Ca,K,Ba)(V5+,V4+)8O20 · 3H2O |
| 4.HE.25 | Häggite | V3+V4+O2(OH)3 |
| 4.HE.30 | Doloresite | V4+3O4(OH)4 |
| 4.HE.35 | Duttonite | V4+O(OH)2 |
| 4.HE.40 | Cavoite | CaV4+3O7 |
Other Information
Thermal Behaviour:
When heated, it passes through various color changes and melts readily.
Notes:
Reversibly dehydrates to metahewettite. Slightly soluble in water.
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
mindat.org URL:
https://www.mindat.org/min-1890.html
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Please feel free to link to this page.
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References for Hewettite
Reference List:
Barnes, W. H., Qurashi, M. M. (1952) Unit cell and space group data for certain vanadium minerals. American Mineralogist, 37 (5-6) 407-422
Bayliss, Peter (1982) X-ray powder data for hewettite. Mineralogical Magazine, 46 (341) 503-504 doi:10.1180/minmag.1982.046.341.18
Evans, Howard T., Jr.,, Hughes, John M. (1990) Crystal chemistry of the natural vanadium bronzes. American Mineralogist, 75 (5-6) 508-521
Oka, Yoshio, Yao, Takeshi, Sato, Shoichi, Yamamoto, Naoichi (1998) Hydrothermal Synthesis and Crystal Structure of Barium Hewettite: BaV6O16·nH2O. Journal of Solid State Chemistry, 140. 219-225 doi:10.1006/jssc.1998.7879
Localities for Hewettite
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.
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Burro Mine, San Miguel County, Colorado, USA