We all know lapis lazuli because of it's intense blue color. The intensity of color is caused by the excitation of one electron into another orbital. Hardness is 5 to 5.5. Ancient Egyptians used it for jewelry. It was referenced in the Old Testament as "sapphire" and was probably the 5th stone making up the breastplate of the high priest. In the Middle Ages painters crushed it into a powder called ultramarine and used it as a dye. In the Renaissance, painters used ultramarine for pigment. Most lapis lazuli today comes from regions in Afghanistan and Pakistan but is also mined in Russia, Chili, Italy, Mongolia, Canada, and the U.S.