Borate mineral

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 [B(O,OH)₄]⁻ 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:

IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). This list uses it to modify the Classification of Nickel–Strunz (mindat.org, 10 ed, pending publication).

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