325mesh black tourmaline powder made in Hebei, China Place of Origin: Hebei, ChinaBrand name: ... .18K2O0.09FeO8.33NaO21.19Cr2O30.22B2O310.16TiO20.44 Typical chemical formula:(Ca,K,Na,[])(Al,Fe,Li,Mg,Mn)3(Al,Cr ... , Fe,V)6(BO3)3(Si,Al,B)6O18(OH,F)4 Typical physical properties:Density2 ...