Discovered in 1876, it is now extensively used as a dye for textiles and for paper and leather.
Manufacturer/ product code: Sigma-Aldrich / M6900
Chemical Description: triaminotriphenylmethane dye, C16H18ClN3S.
Color: blue
Color Index: Basic Blue 9, C.I. 52015
More info:
XRF spectroscopy
XRF Spectroscopy Pigments-Checker DatabaseXRF cannot identify this pigment.