Ultramarine Blue Pigment chemically is Sodium Alumino Sulphosilicate and represent a blue pigment comprising primarily of double silicate of aluminum & sodium with some sulphides / sulfates, Ultramarine pigment occurs in nature as a proximate component of lapis lazuli.
Molecular Formula Ultramarine Blue: Al6Na8O24S3Si6
Today, it is widely accepted in the global markets as the High heat stable Pigment blue 29 for Plastic applications.
This is quite amazing, a detailed cage structure of one particle of ultramarine blue. Its very well described by this picture that how the entrapment of S3 ions develops the unique color in Ultramarine blue Pigments.
This is basically a zeolite cage structure where entrapments of s3- ions happens which causes the blue to reach its destination. We have tried entrapping s2 ions in our research but not desired.