Lapis Lazuli, or Lazurite is an opaque semiprecious stone characterized by its deep violet-blue color. Lapis was the source of the vivid blue pigment known as 'azzurrum ultramarine,' or 'genuine ultramarine' used in fine-art oil paints until its synthesis (synthetic or French ultramarine) in the 1928. Lapis lazuli is not a mineral but a complex aggregate rock colored by lazurite, and containing hauynite, noselite and various other minerals. Lapis Lazuli is often flecked with golden pyrite, sodalite, and/or calcite inclusions. Lapis lazuli commonly forms as veins or layers in crystalline limestone, as a byproduct of contact or thermal metamorphism. Associated minerals are apatite, feldspar, and zircon.
Lapis was treasured by ancient Egyptian and Babylonian civilizations and was often worn by royalty, and the funerary mask of Egyptian king Tutankhamun was heavily decorated with inlayed Lapis Lazuli. Powdered lapis was also used as a pigment in paint, cosmetic eye shadow, and in medicine. Lapis was also a popular gemstone with the ancient Chinese, Greeks, and Romans.
Photo (left) - Jeff & Susan Wise (Aaron Faber Gallery NY)
The first part of the name 'lapis' is Latin, meaning stone. The second part of the name, 'lazuli', is the genitive form of the medieval Latin word lazulum, which came from the Persian word lazhuward meaning "azure" or "blue." Taken as a whole, lapis lazuli means 'stone of azure' or 'blue stone.' Due to its porous and opaque nature, lapis is typically cut and shaped into a cabochon or strung as rough, unpolished nugget-like beads.
Lapis Mining in Sar-e-Sang
Mines at Sar-e-Sang (Sare Sang) located in the Kokcha Valley of Badakhshan Province (Badakshan; Badahsan), Afghanistan (Persian lapis, Afghan lapis) are the principal source for higher-quality lazurite and lapis lazuli today. Secondary sources are in the Lake Baikal region of Siberia, Russia (Siberian lapis) and Ocalle, Chile (chilean lapis).
Lapis Lazuli Composition
Lapis is a rock, not a crystal, and therefor is not identified with a particular crystal system, although crystalline Lazurite does occur with a dodecahedral crystal structure. Lapis has a compact massive" crystal habit, and a hardness of 5 to 5.5 on the Mohs scale. Lapis has a refractive index of 1.610. Lapis has no cleavage and a vitreous to greasy surface luster.
Chemical composition: (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2
Reconstituted or Dyed Lapis Lazuli
Paler, greenish varieties of Chilean lapis are often dyed or acid-washed to obtain a deeper blue color. Dying is accomplished using ferric ferrocyanide (Prussian blue) or other pigments. Selective dying may take place to cover up small white flecks of calcite. Dying can sometimes be detected by swabbing the stone with a Q-tip soaked in acetone or nail-polish remover. Reconstituted lapis is natural stone, or stone fragments that have been pulverized into a powder, soaked in binding agents, then pressed into a solid mass to be re-cut.
Imitation Lapis Lazuli
A lapis imitation known as "Swiss Lapis," or German Lapis" is created from dying paler varieties of chalcedony, ironstone or quartz jasper with ferrocyanide. A Chelsea Filter can be used to distinguish genuine lapis from Swiss lapis which will appear as red.
Lapis lazuli was successfully simulated by Pierre Gilson Sr. of France in the 1970s but the synthetic version is slightly softer than natural lapis. The Gilson version contains flecks of pyrite flakes to imitate the look of Afghan lapis, but does not contain calcite or sodalite inclusions. Sintered synthetic blue spinel was used in the past as a lapis simulant.
Semi-Precious Stones