Ultramarine Blue is a complex, sulphur containing Alumino Silicate whose crystal structure is similar to Sodalite and other Zeolitic materials. The colour is believed to be brought about by the Polysulphide linkage, which is considered to be in a highly resonant state.
The tetrahedron is the fundamental geometric structure upon which the lattice is based. The Aluminium and Silicon atoms occupy the centre of each tetrahedron in a manner resembling the configuration of methane. The Sodium ion have no specific place in the crystal lattice account for the ion exchange properties of the Zeolites in general and Ultramarine in particular.
SYNTHESIS:
Ultramarine Blue now is produced artificially by a prolonged process of heating and cooling cycle. The raw ultramarine blue so produced has to undergo various purification stages till it attains desired fineness and tinting strength.
A typical process flow chart is an indication of the production cycle.
