| Borax | |
| Category: | Nesoborate |
| Formula: | Na2B4O5(OH)4·8H2O |
| Imasymbol: | Brx[1] |
| Strunz: | 6.DA.10 |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | C2/c (no. 15) |
| Unit Cell: | a = 11.8790(2) Å, b = 10.6440(2) Å, c = 12.2012(2) Å; β = 106.617(1)°; Z = 4 |
| Color: | Colorless or white |
| Habit: | As prismatic crystals or as massive encrustations |
| Twinning: | Rare on |
| Cleavage: | Perfect on, less perfect on, very poor on |
| Fracture: | Conchoidal |
| Mohs: | 2 to 2.5 |
| Luster: | Vitreous to resinous to earthy |
| Refractive: | nα = 1.4466 nβ = 1.4687 nγ = 1.4717 |
| Opticalprop: | Biaxial (-) |
| Streak: | White |
| Gravity: | 1.715 |
| Fusibility: | 1.5 |
| Diagnostic: | Froths on heating, producing a yellow flame |
| Solubility: | Soluble in water |
| Diaphaneity: | Translucent to opaque |
| References: | [2] [3] [4] |
Borax (· [2]) is a borate mineral found in evaporite deposits of alkaline lacustrine environments and as a surface efflorescence in arid regions. It is the chief mineral mined from the deposits at Boron, California and nearby locations, and is the chief source of commercial borax.[4]
Borax first reached Western civilization as tincal mined from deposits in Tibet.[4] The term borax comes from the Arabic bauraq, meaning white.
The most extensive deposits are in Kirka, Turkey. Borax is also mined in the Andes Mountains of Argentina, Bolivia, and Chile. However, the greatest production is from the deposits in California.[4]
Natural occurrences of the mineral are an important source of commercial borax, which is used for the manufacture of glass fibers, in cleaning agents, as an antiseptic, and as a flux in metallurgy and solvent for metal oxides.[4]