 The element Boron most often occurs in nature as borates, such as borate minerals and borosilicates.Borates are composed of trigonal planar BO3 or tetrahedral BO4 structural units, joined together via shared oxygen atoms and may be cyclic or linear in structure.The simplest borate anion, the orthoborate(3−) ion, [BO3]3−, is known in the solid state, for example, in Ca3(BO3)2, where it adopts a nearly trigonal planar structure.