An old borax plant in Death Valley, California.

Borate glasses have a more complex action of alkali ions than silicate glasses.^[1] Borate glasses also have major differences in their optical properties.^[2]

The single largest use of boron compounds in the world (accounting for half of total global use) is the production of certain types of boron-treated glass fiber for insulating and structural fiberglass.^[3] In these uses the boron may be present as borax or boron oxide, and adds to the structural strength of the glass as borosilicate, or is added as a fluxing agent to decrease the melting temperature of pure silica, which is difficult to extrude as fibers and work with in pure form, due to the high temperatures involved.

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