Ca,K,Na, )(Al,Fe,Li,Mg,Mn)3(Al,Cr,Fe,V)6 (BO3)3(Si,Al,B)6O18(OH,F)4 [1] [2] Repeating Formula Of Tourmaline https://www.gemjewellerykxo.ca/post/the-elements More About Tourmaline https://geology.com/minerals/tourmaline.shtml Pink Tourmaline https://www.gia.edu/tourmaline