Original: The main component of lapis lazuli is lazurite (25% to 40%), a feldspathoid silicate mineral with the formula (Na, Ca) 8 (AlSiO4) 6 (S, SO4, Cl) 1-2.
Simplified: Lazurite is a silicate mineral with sulfate, sulfur and chloride. Its formula is (Na, Ca) 8 (AlSiO4) 6 (SO4, S, Cl) 2.