Hexahydroborite
A valid IMA mineral species
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About Hexahydroborite
Formula:
Ca[B(OH)4]2 · 2H2O or CaB2O4 · 6H2O
Colour:
Colorless
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
1.84
Crystal System:
Monoclinic
Name:
Named for the composition, originally thought to contain six water molecules, but later found by crystal-structure analysis to be incorrect.
This page provides mineralogical data about Hexahydroborite.
Unique Identifiers
Mindat ID:
1892
Long-form identifier:
mindat:1:1:1892:6
IMA Classification of Hexahydroborite
Classification of Hexahydroborite
6.AC.25
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
26.1.4.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
1 : Monoborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
1 : Monoborates
9.3.16
9 : Borates
3 : Borates of Ca and Sr
9 : Borates
3 : Borates of Ca and Sr
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 |
|---|---|---|
| Hhb | 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 Hexahydroborite
Vitreous
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Hardness:
2½ on Mohs scale
Cleavage:
Perfect
Perfect normal to the plane 12° from Z. Also an imperfect cleavage.
Perfect normal to the plane 12° from Z. Also an imperfect cleavage.
Density:
1.84 g/cm3 (Measured)
Optical Data of Hexahydroborite
Type:
Biaxial (+)
RI values:
nα = 1.498 nβ = 1.503 nγ = 1.51
2V:
Measured: 83° , Calculated: 82°
Max. Birefringence:
δ = 0.012
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
Dispersion:
very weak
Optical Extinction:
X ∧ c = 14°.
Chemistry of Hexahydroborite
Mindat Formula:
Ca[B(OH)4]2 · 2H2O or CaB2O4 · 6H2O
Element Weights:
Elements listed:
Crystallography of Hexahydroborite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 8 Å, b = 6.64 Å, c = 8.01 Å
β = 104.21°
β = 104.21°
Ratio:
a:b:c = 1.205 : 1 : 1.206
Unit Cell V:
412.47 ų (Calculated from Unit Cell)
Comment:
A axis may be 16.011 (Fuka)
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) |
|---|---|---|---|---|---|---|---|
| 0009398 | Hexahydroborite | Sedlacek P, Dornberger-Schiff K (1971) An OD-Disordered modification of the calcium monoborate dihydrate Ca[B(OH)4]2*2H2O Acta Crystallographica B27 1532-1541 |  | 1971 | synthetic | 0 | 293 |
| 0009397 | Hexahydroborite | Sedlacek P, Dornberger-Schiff K (1971) An OD-Disordered modification of the calcium monoborate dihydrate Ca[B(OH)4]2*2H2O Acta Crystallographica B27 1532-1541 | | 1971 | synthetic | 0 | 293 |
| 0015534 | Hexahydroborite | Ozol Y, Vimba S, Ievins A (1964) The crystal structure of calcium monoborate Ca[B(OH)4]2*2H2O Soviet Physics 9 22-25 | 1964 | synthetic | 0 | 293 | |
| 0012453 | Hexahydroborite | Simonov M A, Yamnova N A, Kazanskaya E V, Egorov-Tismenko Y K, Belov N V (1976) Crystal structure of Ca(B(OH)4)2(H2O)2 Doklady Akademii Nauk SSSR 228 1337-1340 | 1976 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.73 Å | (100) |
| 3.37 Å | (90 broad) |
| 3.118 Å | (90) |
| 2.550 Å | (90) |
| 2.792 Å | (80) |
| 2.469 Å | (80) |
| 2.283 Å | (80) |
| 1.961 Å | (70) |
| 1.931 Å | (70) |
Comments:
Solongo deposit, Russia. Data from Simonov et al. (1977).
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 Hexahydroborite
General Appearance of Type Material:
Aggregates of flattened prismatic colorless crystals to 0.5 mm.
Place of Conservation of Type Material:
Russian Institute of Mineral Resources, Moscow, Russia.
Moscow University, Moscow, Russia.
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 80438.
Moscow University, Moscow, Russia.
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 80438.
Geological Setting of Type Material:
Boron-rich skarn deposits in metasomatized limestone.
Associated Minerals at Type Locality:
Synonyms of Hexahydroborite
Other Language Names for Hexahydroborite
Dutch:Hexahydroboriet
German:Hexahydroborit
Russian:Гексагидроборит
Simplified Chinese:六方水硼石
Spanish:Hexahydroborita
Traditional Chinese:六方水硼石
Common Associates
Associations Based on Photo Data:
| 1 photo of Hexahydroborite associated with Chrysoberyl | BeAl2O4 |
Related Minerals - Strunz-mindat Grouping
| 6.AC.05 | Sinhalite | MgAl(BO4) |
| 6.AC.10 | Pseudosinhalite | Mg2Al3(BO3)2(OH)O3 |
| 6.AC.15 | Béhierite | Ta(BO4) |
| 6.AC.15 | Schiavinatoite | Nb(BO4) |
| 6.AC.20 | Frolovite | Ca[B(OH)4]2 |
| 6.AC.30 | Henmilite | Ca2Cu[B(OH)4]2(OH)4 |
| 6.AC.35 | Bandylite | Cu[B(OH)4]Cl |
| 6.AC.40 | Teepleite | Na2[B(OH)4]Cl |
| 6.AC.45 | Moydite-(Y) | Y[B(OH)4](CO3) |
| 6.AC.50 | Carboborite | Ca2Mg[B(OH)4]2(CO3)2 · 4H2O |
| 6.AC.55 | Sulfoborite | Mg3[B(OH)4]2(SO4)(OH,F)2 |
| 6.AC.60 | Lüneburgite | Mg3[B2(OH)6](PO4)2 · 6H2O |
| 6.AC.65 | Seamanite | Mn2+3[B(OH)4](PO4)(OH)2 |
| 6.AC.70 | Cahnite | Ca2[B(OH)4](AsO4) |
Other Information
Notes:
Easily soluble in dilute HCl or in alcohol; slowly soluble in water (room temperature).
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 Hexahydroborite
mindat.org URL:
https://www.mindat.org/min-1892.html
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References for Hexahydroborite
Reference List:
Fleischer, Michael, Cabri, Louis J., Pabst, and Adolf (1977) New mineral names. American Mineralogist, 62 (11-12) 1259-1262
Localities for Hexahydroborite
Showing 3 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.
Japan | |
| Kusachi et al. (1999) |
Kazakhstan | |
| Малинко С.В. |
Russia (TL) | |
| M.A. Simonov et al.: ZVMO 106:691-697 (1977) +3 other references |
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Solongo B deposit, Ozernoe ore cluster, Yeravninsky District, Buryatia, Russia