Boric acid (also known as sassolite, H3BO3) nearly always plays a role in the formation of boron minerals
Williams 1996. Therefore, it would make sense that the acid would contribute, in some shape or form, to the formation of pegmatites containing boron minerals such as axinite. As it turns out, a 1990's discovery found fluid inclusions of boric acid within pegmatites around the world
Williams 1996. It is then possible that the liquid that was so essential for pegmatite formation may have been, to some extent, boric acid. However, the extent to which these boric acid inclusions influenced the formation of pegmatites is not entirely known, however evidence supporting the link between the two is still being discovered. In fact, a method to calculate the concentration of boric acid in these inclusions have been applied to many pegmatites from a multitude of world regions to be compared. Figure 4 below displays the three way solubility diagram between water, boric acid, and NaCl at different temperatures in pegmatites
Williams 1996. This, perhaps, may explain the crucial roles that both water and boric acid played in pegmatite formation.
There are other ways that boron may have played a role in pegmatite formation. One of the leading theories behind this idea draws on boron's characteristic as a fluxing element. This means that increased levels of
boron can have the effect of essentially lowering the temperature of solidification in the late-stage magma
Lee 1999. Therefore, the role of boron in pegmatite formation may have been to alter the conditions (lower the temperature) to the point at which minerals including incapable elements could solidify.
Overall, however, examining these sample offers scientists the ability to use the boron as a kind of thermometer for the temperature at the time that these crystals actually solidified. Having this information gives researchers further insights into the conditions necessary, and the conditions that existed, to create new, rare minerals.