“…Minerals of the tourmaline supergroup are (Si6O18)-ring borosilicates with much diversified compositions. They occur as minor to accessory minerals in low-grade to ultrahigh-pressure metamorphic rocks, granites and granitic pegmatites, chemically resistant phases in sedimentary rocks, as well as common gangue minerals in diverse types of hydrothermal deposits (e.g., Ertl et al 2010;Slack and Trumbull 2011;van Hinsberg et al 2011;Henry and Dutrow 2012;Biernacka 2019). According to Henry et al (2011), the general chemical formula of the tourmaline supergroup minerals can be written as XY3Z6(T6O18)(BO3)3V3W, where the populations of cations and anions at specific structural sites are indicated in capital letters: IX X = Na + , K + , Ca 2+ , Pb 2+ , ( = vacancy); VI Y = Fe 2+ , Mg 2+ , Mn 2+ , Al 3+ , Li + , Fe 3+ , Cr 3+ , V 3+ , Ti 4+ , Zn 2+ , Cu 2+ , Ni 2+ ; VI Z = Al 3+ , Fe 3+ , Cr 3+ , V 3+ , Mg 2+ , Fe 2+ ,Ti 4+ ; IV T = Si 4+ , Al 3+ , B 3+ ; III B = B 3+ ; III,IV V = OH -, O 2-; and III,IV W = OH -, F -, O 2-.…”