The borate minerals are minerals which contain a borate anion group. The borate (BO3) units may be polymerised similar to the SiO4 unit of the silicate mineral class. This results in B2O5, B3O6, B2O4 anions as well as more complex structures which include hydroxide or halogen anions. The - anion exists too.
Many borate minerals, such as borax, colemanite, and ulexite, are salts: soft, readily soluble, and found in evaporite contexts. However, some, such as boracite, are hard and resistant to weathering, more similar to the silicates.
There are over 100 different borate minerals. Borate minerals include:
- Kernite Na2B4O6(OH)3·3(H2O)
- Borax Na2B4O5(OH)4·8(H2O)
- Ulexite NaCaB5O6(OH)6·5(H2O)
- Colemanite CaB3O4(OH)3·(H2O)
- Boracite Mg3B7O13Cl
Read more about Borate Minerals: Nickel–Strunz Classification -06- Borates