Johachidolite, CaAl[B3O7], a mineralogical and structural peculiarity

Crystal Chemistry of High-Temperature Borates

“…The structures of binary and more complex borates predominantly contain isolated BO3 triangles, less frequently tetrahedra or pyrogroups (Figure 4a). Only in four types of layered structures, i.e., in jochachidolite, synthetic RCo(BO2)5 with R = La − Ho, Na2Zn2MnB4.67O11 and RAl2B4O10.5 with R = La − Nd [33][34][35][36][37], one can identify sextuple, quadruple and binary three-membered rings (Figure 4b-f).…”

“…(a) (2∆) kurchatovite, CaMg(B2O5) [33] (b) (4t) (c) (6t) johachidalite, CaAl(B3O7) [34] (d) (6t) NdAl2.07(B4O10)O0.60 [35] (e) (2∆ + 3t) (f) (4t) RCo(BO2)5 [36] [35]; (e) and (f) RCo(BO2)5 [36].…”

“…BaO4B2O3 [48] (j) (2∆ + 2t) + (1∆) + (1∆) R(BO2)3 [27] (k) (3t) johachidalite, CaAl(B3O7) [34] (l) (2t) RAl-metaborates (R = Ce-Nd)…”

“…In simple R metaborates (N = 1/3), the polyanions are chain-like with n = 2. Simultaneously, in binary borates of tri-and divalent metals, for example, johachidolite CaAlB 3 O 7 [34], synthetic RCo(BO 2 ) 5 [71] and RAl 2 B 4 O 10.5 [35] the polyanions are represented by layers of BO 4 -tetrahedra or BO 4 -tetrahedra together with BO 3 -triangles, even if the N value is equal to 2/3, 2/5 and 3/4, respectively. Most likely, the nature of metals plays a significant role here.…”

“…Examples of CSU in binary and more complex borates (the green and red balls represent B, and O atoms, respectively). (a) kurchatovite, CaMg(B2O5)[33]; (b) and (c) johachidalite, CaAl(B3O7)[34]; (d) NdAl2.07(B4O10)O0.60…”