Investigations on boron-rich tourmaline with the formula NaAl₃Al₆(Si₃B₃O₁₈)(BO₃)₃(OH)₃(OH)

Recently, ertlite, NaAl3Al6(Si4B2O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup was described by CEMPÍREK et al. (2025). This is the first tourmaline in which boron (B) occurs in the endmember formula. Ertlite was described from two localities. The Brichest tourmaline sample exhibits lattice parameters of a = 15.590(2), c = 7.009(1) Å, and an empirical formula of ~(Na0.74Ca0.110.15)(Al2.84Li0.15Fe0.01)Al6.00(Si4.05B1.95O18)(BO3)3(OH)3 [O0.72(OH)0.24F0.04]. Here, we describe an even more B-rich tourmaline with the approximate formula NaAl3Al6(Si3B3O18)(BO3)3(OH)3(OH).