Opaque to translucent precious gemstone composed mainly of lazurite and calcite. Its name originates from the Persian word "lazhward", which was the name of a place in modern Turkestan known for its deposits of lapis lazuli "stone of lazhward". The finest colour is intense blue, lightly dusted with small flecks of golden pyrite. In the past it was also ground and processed to make the pigment ultramarine for tempera paint and oil paint.

Source: Encyclopedia of gemstones and minerals.