Occurrence of The group 13 elements

   The relative abundances of the group 13 elements are shown in Figure 1.1. The main sources of boron are borax, Na₂ [B₄O₅(OH)₄]. 8H₂O, and kernite, Na₂ [B₄O₅(OH)=]. 2H₂O, with extensive deposits being worked commercially in the Mojave Desert, California. Aluminium is the most abundant metal in the Earth’s crust, and occurs in aluminosilicates (see Section 13.9) such as clays, micas and feldspars, in bauxite (hydrated oxides) and, to a lesser extent, in cryolite, Na₃[AlF₆]. Gallium, indium and thallium occur in trace amounts as sulfides in various minerals.

Fig. 1.1 Relative abundances of the group 13 elements in the Earth’s crust. The data are plotted on a logarithmic scale. The units of abundance are parts per billion; 1 billion = 10⁹.