Our project consisted of the historical uses of pigment azurite in fresco, tempera, and oil paintings from the 1400s to the 1600s. Azurite was one of the popular blue pigments in the Middle Ages and Early Renaissance. It is a copper based mineral that has a greenish blue hue. Azurite always contains impurities so it reflects not only blue light, but also other colors from the spectrum. The finer the azurite is ground, the paler it is. Azurite was a less expensive blue pigment than ultramarine and that made it very popular as a substitute during those time periods. Azurite has a dark tone, so it was often used as a base layer in paintings for modeling effects. However, azurite has many limitations. For example, it cannot be mixed with water, which means it can only be used in fresco a secco. It also degrades over time, which results in color change.