Borax
A valid IMA mineral species - grandfathered
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About Borax
Formula:
Na2(B4O5)(OH)4 · 8H2O
Colour:
Colourless, grey, white, yellowish, seldom bluish or greenish; colourless in transmitted light.
Lustre:
Vitreous, Resinous, Earthy
Hardness:
2 - 2½
Specific Gravity:
1.715
Crystal System:
Monoclinic
Name:
From the Arabic bauraq, meaning "white", which also included niter and natron of the time.
Type Locality:
Unique Identifiers
Mindat ID:
722
Long-form identifier:
mindat:1:1:722:1
GUID
(UUID V4):
(UUID V4):
55e593a7-ab4d-4202-8b58-9ce2d58a8a00
IMA Classification of Borax
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Na2B4O5(OH)4 · 8H2O
Classification of Borax
6.DA.10
6 : BORATES
D : Tetraborates
A : Neso-tetraborates
6 : BORATES
D : Tetraborates
A : Neso-tetraborates
26.4.1.1
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
4 : Tetraborates
26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
4 : Tetraborates
9.1.9
9 : Borates
1 : Borates of the alkalis and boric acid
9 : Borates
1 : Borates of the alkalis and boric acid
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Brx | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Brx | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Pronunciation of Borax
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Borax
Vitreous, Resinous, Earthy
Transparency:
Translucent, Opaque
Colour:
Colourless, grey, white, yellowish, seldom bluish or greenish; colourless in transmitted light.
Streak:
White
Hardness:
2 - 2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
On {100} perfect; on {110} less perfect; on {010} in traces.
On {100} perfect; on {110} less perfect; on {010} in traces.
Fracture:
Conchoidal
Density:
1.715(2) g/cm3 (Measured) 1.7 g/cm3 (Calculated)
Comment:
Measured density of the pure chemical compound
Optical Data of Borax
Type:
Biaxial (-)
RI values:
nα = 1.447 nβ = 1.469 nγ = 1.472
2V:
Measured: 39° to 40°, Calculated: 32° to 40°
Max Birefringence:
δ = 0.025
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v distinct
Optical Extinction:
X = b; Z ∧ c = –55°35′.
Chemistry of Borax
Mindat Formula:
Na2(B4O5)(OH)4 · 8H2O
Elements listed:
Crystallography of Borax
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 12.2012(2) Å, b = 10.644 Å, c = 11.879 Å
β = 106.617(1)°
β = 106.617(1)°
Ratio:
a:b:c = 1.146 : 1 : 1.116
Unit Cell V:
1,478.29 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals commonly short-prismatic [001] and often rather tabular {100}. Prominent zones [001] and [110]. Faces "m," "o," and "z" often striated parallel to [110]. Crystals often malformed through abnormal development of part of one or more zones.
Twinning:
On {100}, rare.
Crystallographic forms of Borax
Crystal Atlas:
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Borax no.8 - Goldschmidt (1913-1926)
Borax no.11 - Goldschmidt (1913-1926)
Borax no.28 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by
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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) |
|---|---|---|---|---|---|---|---|
| 0009647 | Borax | Levy H A, Lisensky G C (1978) Crystal structures of sodium sulfate decahydrate (Glauber's salt) and sodium tetraborate decahydrate (borax). Redetermination by neutron diffraction Acta Crystallographica B34 3502-3510 |  | 1978 | Synthetic | 0 | 293 |
| 0019359 | Borax | Gainsford G J, Kemmitt T, Higham C (2008) Redetermination of the borax structure from laboratory X-ray data at 145 K Acta Crystallographica E64 i24-i25 | | 2008 | synthetic | 0 | 145 |
| 0019358 | Borax | Morimoto N (1956) The crystal structure of borax Mineralogical Journal 2 1-18 | 1956 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.576 Å | (100) |
| 2.565 Å | (95) |
| 4.86 Å | (80) |
| 2.848 Å | (65) |
| 2.833 Å | (60) |
| 5.69 Å | (50) |
| 3.936 Å | (45) |
Comments:
Synthetic.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) |
Geological Setting:
In evaporite deposits, salt lakes, playas, and efflorescences on soils in arid regions, in solution in hot springs.
Type Occurrence of Borax
Synonyms of Borax
Other Language Names for Borax
Armenian:Buraq
Bengali:বোরাক্স
Bosnian:Boraks
Catalan:Bòrax
Czech:Tetraboritan sodný
Dutch:Borax
Esperanto:Borakso
Farsi/Persian:Būrah
French:Borax
Soude boratée
Soude boratée
Galician:Bórax
Hindi:Tinkál
Hungarian:Bórax
Indonesian:Bleng
Irish Gaelic:Bórás
Italian:Borace
Japanese:ホウ砂
Latin:Borras
Lithuanian:Boraksas
Polish:Boraks rodzimy
Portuguese:Bórax
Romanian:Borax
Russian:Бура
Serbian:Боракс
Simplified Chinese:硼砂
Spanish:Bórax
Swedish:Borax
Traditional Chinese:硼砂
Turkish:Boraks
Ukrainian:Бура
Vietnamese:Borac
Common Associates
Associated Minerals Based on Photo Data:
| 19 photos of Borax associated with Tincalconite | Na2(B4O7) · 5H2O |
| 6 photos of Borax associated with Sulphohalite | Na6(SO4)2FCl |
| 4 photos of Borax associated with Ulexite | NaCa[B5O6(OH)6] · 5H2O |
| 3 photos of Borax associated with Hanksite | Na22K(SO4)9(CO3)2Cl |
Related Minerals - Strunz-mindat Grouping
| 6.DA.15 | Tincalconite | Na2(B4O7) · 5H2O |
| 6.DA.20 | Hungchaoite | Mg(B4O7) · 9H2O |
| 6.DA.25 | Fedorovskite | Ca2Mg2B4O7(OH)6 |
| 6.DA.25 | Roweite | Ca2Mn2+2B4O7(OH)6 |
| 6.DA.30 | Hydrochlorborite | Ca4B8O15Cl2 · 21H2O |
| 6.DA.35 | Uralborite | Ca2[B3O3(OH)5 · OB(OH)3] |
| 6.DA.40 | Borcarite | Ca4Mg(B4O6(OH)6)(CO3)2 |
| 6.DA.40 | Numanoite | Ca4Cu(B4O6(OH)6)(CO3)2 |
| 6.DA.60 | Fontarnauite | (Na,K)2(Sr,Ca) (SO4)[B5O8(OH)] · 2H2O |
Other Information
IR Spectrum:
Siberian material [cm-1]: 3510s, 3410s, 3200sh, 1660sh, 1640, 1413s, 1385sh, 1330sh, 1180sh, 1127, 1070s, 1025sh, 996, 855sh, 830sh, 807, 760sh, 687sh, 652sh, 610
Magnetism:
Diamagnetic
Thermal Behaviour:
Melting point: 878 °C. The melt dissolves numerous metal oxides.
Loses 5 mol of water when heated to 100°C, another 4 mol when heated to 150 °C, and the last mol at 400 °C.
Loses 5 mol of water when heated to 100°C, another 4 mol when heated to 150 °C, and the last mol at 400 °C.
Notes:
Rapidly dehydrates in air to tincalconite. Soluble in water - slightly in cold water readily in boiling water. Insoluble in ethanol.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Boron ore
Borax in petrology
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Internet Links for Borax
mindat.org URL:
https://www.mindat.org/min-722.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Borax
Localities for Borax
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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Rio Tinto Borax open pit, Rio Tinto Borax Mine, Kramer Borate deposit, Boron, Kern County, California, USA