Schorl tourmaline
Schorl is a mineral with formula of NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH or NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH). The corresponding IMA (International Mineralogical Association) number is IMA2007 s.p.. The IMA symbol is Srl.