Historically a very expensive ground lazurite pigment, synthetic pigment has been used since the 1830's making it one of the most popular and affordable blues.
Pigment Classification: Inorganic
Color Index Name: PB29
Color Index Number: 77007
Chemical Description: Polysulfide of Sodium-Alumino-Silicate
Lightfastness Rating: ASTM 1
Permanency: Not for Exterior Use