n CdS·HgS. Pigment Orange 23 (77201). A series of cadmium/mercury sulfides of mixed crystal composition. Colors vary according to CdS/HgS ratio from deep orange to maroon. Known for high heat stability, solvent insolubility, good chemical resistance, and excellent lightfastness. CdS/HgS ratio, 89.1/10.9. Density 4.8–5.2 g/cm³ (40–43 lb/gal); O.A., 33.2; particle size, 0.1–1.0 μm. Syn:  Mercadium®,  Mercury Cadmium Cadmium Red/Orange and  Cadium Orange.