Wightmanite
A valid IMA mineral species
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About Wightmanite
Formula:
Mg5(BO3)O(OH)5 · 2H2O
Colour:
Colourless or light green
Lustre:
Vitreous
Hardness:
5½
Specific Gravity:
2.60
Crystal System:
Monoclinic
Name:
Named after Randall H. Wightman (1915-1969), director of exploration and mining, Riverside Cement Company (California, USA).
This page provides mineralogical data about Wightmanite.
Unique Identifiers
Mindat ID:
4287
Long-form identifier:
mindat:1:1:4287:7
IMA Classification of Wightmanite
Approved
IMA Formula:
Mg5O(BO3)(OH)5·2H2O
First published:
1962
Classification of Wightmanite
6.AB.55
6 : BORATES
A : Monoborates
B : BO3, with additional anions; 1(D) + OH, etc.
6 : BORATES
A : Monoborates
B : BO3, with additional anions; 1(D) + OH, etc.
26.1.2.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
1 : Monoborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
1 : Monoborates
9.2.7
9 : Borates
2 : Borates of Be and Mg
9 : Borates
2 : Borates of Be and Mg
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 |
|---|---|---|
| Wmn | 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 Wightmanite
Vitreous
Transparency:
Translucent
Colour:
Colourless or light green
Streak:
White
Hardness:
5½ on Mohs scale
Cleavage:
Perfect
{010} perfect, {100} fair; the two making an angle of 73.5 deg.
{010} perfect, {100} fair; the two making an angle of 73.5 deg.
Density:
2.60 g/cm3 (Measured) 2.58 g/cm3 (Calculated)
Optical Data of Wightmanite
Type:
Biaxial (-)
RI values:
nα = 1.585(3) nβ = 1.603(3) nγ = 1.604(4)
2V:
Measured: 33° , Calculated: 26°
Max. Birefringence:
δ = 0.019
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 (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:
strong, r
Comments:
Z∧c = 5°; OAP∧{010} ~8°
Chemistry of Wightmanite
Mindat Formula:
Mg5(BO3)O(OH)5 · 2H2O
Element Weights:
Elements listed:
Crystallography of Wightmanite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 13.46(2) Å, b = 3.102(5) Å, c = 18.17(2) Å
β = 91.60(5)°
β = 91.60(5)°
Ratio:
a:b:c = 4.339 : 1 : 5.858
Unit Cell V:
758.35 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic, no terminations found on type material.
Invariably present and important: {010}, {100}, and {110}.
Present but usually narrow: {430}, {530}, {510}, {310}, {320}, {430}, and {150}.
Invariably present and important: {010}, {100}, and {110}.
Present but usually narrow: {430}, {530}, {510}, {310}, {320}, {430}, and {150}.
Comment:
Space Group: I2/m.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
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View
CIF File Best | x | y | z | a | b | c
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Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
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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) |
|---|---|---|---|---|---|---|---|
| 0014684 | Wightmanite | Moore P B, Araki T (1972) Wightmanite, Mg5(O)(OH)5(BO3)*nH2O, a natural drainpipe Nature Physical Science 236 25-26 | 1972 | Crestmore, California, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.70 Å | (100) |
| 9.07 Å | (100) |
| 3.03 Å | (30) |
| 2.67 Å | (30) |
| 4.74 Å | (20) |
| 2.446 Å | (20) |
| 2.35 Å | (20) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) |
Type Occurrence of Wightmanite
General Appearance of Type Material:
Colorless, roughly hexagonal prisms or clusters of prisms in a matrix of coarsely crystalline carbonate rock.
Place of Conservation of Type Material:
n.d.
Associated Minerals at Type Locality:
Other Language Names for Wightmanite
Common Associates
Associations Based on Photo Data:
| 10 photos of Wightmanite associated with Dolomite | CaMg(CO3)2 |
| 3 photos of Wightmanite associated with Lizardite | Mg3(Si2O5)(OH)4 |
| 2 photos of Wightmanite associated with Fluoborite | Mg3(BO3)(F,OH)3 |
| 1 photo of Wightmanite associated with Magnesioferrite | MgFe3+2O4 |
| 1 photo of Wightmanite associated with Ludwigite | Mg2Fe3+(BO3)O2 |
| 1 photo of Wightmanite associated with Spinel | MgAl2O4 |
| 1 photo of Wightmanite associated with Calcite | CaCO3 |
Related Minerals - Strunz-mindat Grouping
| 6.AB. | Chubarovite | KZn2(BO3)Cl2 |
| 6.AB. | Rhabdoborite-(Mo) | Mg12Mo6+1.33O6(BO3)6F2 |
| 6.AB.05 | Hambergite | Be2(BO3)(OH) |
| 6.AB.10 | Berborite | Be2(BO3)(OH) · H2O |
| 6.AB.15 | Jeremejevite | Al6(BO3)5(F,OH)3 |
| 6.AB.20 | Yuanfuliite | Mg(Fe3+,Al)O(BO3) |
| 6.AB.20 | Warwickite | (Mg,Ti,Fe,Al)2O(BO3) |
| 6.AB.25 | Karlite | (Mg,Al)6.5(BO3)3(OH)4(◻,Cl)0.5 |
| 6.AB.30 | Marinaite | Cu2Fe3+O2(BO3) |
| 6.AB.30 | Savelievaite | Mg2Cr3+O2(BO3) |
| 6.AB.30 | Fredrikssonite | Mg2Mn3+O2(BO3) |
| 6.AB.30 | Vonsenite | Fe2+2Fe3+(BO3)O2 |
| 6.AB.30 | Ludwigite | Mg2Fe3+(BO3)O2 |
| 6.AB.30 | Azoproite | (Mg,Fe2+)2(Fe3+,Ti,Mg)(BO3)O2 |
| 6.AB.30 | Bonaccordite | Ni2Fe3+(BO3)O2 |
| 6.AB.35 | Folvikite | Sb5+Mn3+(Mg,Mn2+)10O8(BO3)4 |
| 6.AB.35 | Pinakiolite | (Mg,Mn2+)2Mn3+(BO3)O2 |
| 6.AB.40 | Takéuchiite | (Mg,Mn2+)2(Mn3+,Fe3+)(BO3)O2 |
| 6.AB.40 | Blatterite | Sb5+3(Mn3+,Fe3+)9(Mn2+,Mg)35(BO3)16O32 |
| 6.AB.40 | Orthopinakiolite | (Mg,Mn2+)2Mn3+(BO3)O2 |
| 6.AB.40 | Chestermanite | Mg2(Fe3+,Mn3+,Al,Sb3+)(BO3)O2 |
| 6.AB.45 | Aluminomagnesiohulsite | (Mg,Fe2+)2(Al,Mg,Sn)(BO3)O2 |
| 6.AB.45 | Hulsite | Fe2+2Fe3+O2(BO3) |
| 6.AB.45 | Magnesiohulsite | Mg2Fe3+O2(BO3) |
| 6.AB.50 | Fluoborite | Mg3(BO3)(F,OH)3 |
| 6.AB.50 | Hydroxylborite | Mg3(BO3)(OH)3 |
| 6.AB.55 | Shabynite | Mg5(BO3)(OH)5(Cl,OH)2 · 4H2O |
| 6.AB.60 | Gaudefroyite | Ca4Mn3+2-3(BO3)3(CO3)(O,OH)3 |
| 6.AB.65 | Sakhaite | Ca48Mg16(BO3)32(CO3)16 · 2(H2O,HCl) |
| 6.AB.70 | Harkerite | Ca48Mg16[AlSi4O15(OH)]4(BO3)16(CO3)16 · 2(H2O,HCl) |
| 6.AB.75 | Pertsevite-(F) | Mg2(BO3)(F,OH) |
| 6.AB.75 | Pertsevite-(OH) | Mg2(BO3)(OH) |
| 6.AB.80 | Jacquesdietrichite | Cu2(H2BO3)(OH)3 |
| 6.AB.85 | Rhabdoborite-(V) | Mg12(V5+,Mo6+,W6+)1.5O6{[BO3]6-x[(P,As)O4]xF2-x} (x < 1) |
| 6.AB.85 | Rhabdoborite-(W) | Mg12(W6+,V5+)1.5O6{[BO3]6-x[(P,As)O4]xF2-x} |
| 6.AB.85 | Painite | CaZrAl9(BO3)O15 |
| 6.AB.90 | Mengxianminite | (Ca,Na)2Sn2(Mg,Fe)3Al8[(BO3)(BeO4)O6]2 |
Other Information
Notes:
- Infusible, but on heating turns a golden brown color.
- Soluble in acids with difficulty.
- In the closed tube it turns golden brown, and yields water, but only at moderately high temperature.
- Perfectly clear fragments in hot acid do not effervesce (showing absence of CO2).
- Soluble in acids with difficulty.
- In the closed tube it turns golden brown, and yields water, but only at moderately high temperature.
- Perfectly clear fragments in hot acid do not effervesce (showing absence of CO2).
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 Wightmanite
mindat.org URL:
https://www.mindat.org/min-4287.html
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References for Wightmanite
Reference List:
Murdoch, Joseph (1962) Wightmanite, a new borate mineral from Crestmore, California. American Mineralogist, 47 (5-6) 718-722
MOORE, P. B., ARAKI, T. (1972) Wightmanite, Mg5(O)(OH)5[BO3]·nH2O, a Natural Drainpipe. Nature Physical Science, 239. 25-26 doi:10.1038/physci239025a0
Localities for Wightmanite
Showing 4 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.
Spain | |
| González-Pérez et al. (2023) |
USA | |
| Pemberton (1983) +1 other reference |
| Erd et al. (1988) | |
| Murdoch (1962) +4 other references |
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Commercial Quarry, Sky Blue Hill, Crestmore quarries, Crestmore, Jurupa Valley, Riverside County, California, USA