Lapis lazuli
| Lapis lazuli | |
|---|---|
 A generated image of polished lapis lazuli. The gold flecks are the generator's idea of pyrite. | |
| General | |
| Category | Metamorphic rock, chiefly lazurite |
| Formula | Lazurite: (Na,Ca)8(Al6Si6O24)(S,Cl,SO4,OH)2 |
| Crystal system | Isometric (lazurite) |
| Identification | |
| Color | Deep blue, with white and gold flecks |
| Mohs scale hardness | 5 to 5.5 |
Lapis lazuli is a deep-blue metamorphic rock that people have cut as a gemstone and ground as a pigment for thousands of years. Its color comes from the mineral lazurite, which typically makes up 30 to 40 percent of the stone, and white calcite and flecks of golden pyrite are the usual companions.[1] The best-known source is the Sar-e-Sang mines in the Kokcha valley of Badakhshan, in northeastern Afghanistan, which have been worked for more than 6,000 years.[1] Ground and purified, the stone gives the pigment ultramarine, a name that means "beyond the sea".[2]
Composition
Lapis lazuli is a rock, a mixture of minerals. The blue mineral, lazurite, belongs to the sodalite group of the feldspathoids and crystallizes in the isometric system, though well-formed crystals are rare. It has a Mohs hardness of 5 to 5.5 and was first described as a mineral in 1890, from the Sar-e-Sang district.[3] The color is attributed to the S3- ion, a chain of three sulfur atoms carrying one extra electron, held in the cages of the aluminosilicate framework.[4] The gold flecks are pyrite, a separate mineral, and the white veins are calcite.[1]
The name comes from the Latin lapis, "stone", and the Medieval Latin lazulum, which descends through Arabic from the Persian lāžward; the same Arabic word gave English "azure".[1] Pliny the Elder described the stone as "opaque and sprinkled with specks of gold", and Theophrastus called it sapphirus, "speckled with gold". In late antiquity and the Middle Ages lapis was often called sapphire, in Latin sapphirus, though it is unrelated to the blue corundum that now carries the name.[1]
Sources and early use
The royal tombs of Ur, of the third millennium BC, held a dagger with a lapis handle together with beads, amulets and inlays, and the funerary mask of Tutankhamun is inlaid with the stone.[1] Other deposits include one in the Andes near Ovalle in Chile and one west of Lake Baikal in Russia.[1]
Ultramarine
From about 1200 to the nineteenth century, European painters imported the stone from the Sar-e-Sang mines by way of Baghdad, Damascus, Cyprus and the Italian ports, and making the pigment was a chore that involved lye, wax and plenty of labor.[5] The ground stone was mixed with melted wax, resin and oil, wrapped in cloth and kneaded in a lye made from wood ash. The blue particles settled out, and the step was repeated at least three times, each extraction giving a lower quality than the one before. Al-Tifashi, who died in 1254, is the first to describe the method, and the fifteenth-century treatise of Cennino Cennini brought it to Europe.[2] The pigment was at times valued as highly as gold, and painters reserved the best of it for the Virgin Mary and the Christ child.[2]
Johannes Vermeer painted with natural ultramarine in works such as The Milkmaid.[6][a] In 1824 the Société d'Encouragement pour l'Industrie Nationale offered 6,000 francs for an artificial ultramarine. Jean-Baptiste Guimet devised a process in 1826 and kept it secret; Christian Gmelin devised one in 1828 and published it, and he is credited with starting the artificial industry. The synthetic pigment, which has the Color Index name Pigment Blue 29, is made from kaolin, sodium sulfate, sodium carbonate, sulfur and charcoal, heated at 700 to 750 °C and then oxidized in air at 350 to 450 °C.[2] It became available in the early nineteenth century and largely ended the use of the natural pigment in oil paint.[1]
At Molecular Reality Corporation
During 2025 a long knowledge base written in the voice of the mascot Keltar answered questions about Molecular Reality Corporation, among them one about the case of the older handheld, the MR1 Molecular Streaming Device. "Do you really offer lapis lazuli?" it begins. The answer: "Yes, we'll get the lapis lazuli filament and make you a lapis lazuli case. And several other colors."[8] The filament is the plastic that a 3D printer melts, and lapis lazuli is one of the colors in which the case was to be offered. Instructions for the chatbot in May 2026 still described the case as "available in various colors including lapis lazuli", and said in the same month: "We are not ready to ship MR series Molecular Streaming Devices."[8]
The company's own pictures of the prototype, in its tutorial animation and in its photograph of ten devices, show a red case.[8]
See also
Notes
- ^ Vermeer died on December 15, 1675. On September 30, 1676, Antonie van Leeuwenhoek was appointed curator of the estate of Vermeer's widow.[7]
References
- ^ a b c d e f g h "Lapis lazuli". Wikipedia. Retrieved October 25, 2026.
- ^ a b c d "Ultramarine". Wikipedia. Retrieved October 25, 2026.
- ^ "Lazurite". Wikipedia. Retrieved October 25, 2026.
- ^ "The nature of the chalcogen colour centres in ultramarine-type solids". Chemical Society Reviews 28: 75-84. 1999. doi:10.1039/a704920j.
- ^ "Making colour". Nature. 2014.
- ^ "Johannes Vermeer". Wikipedia. Retrieved October 25, 2026.
- ^ "Vermeer chronology". Lens on Leeuwenhoek. Retrieved October 25, 2026.
- ^ a b c "Company records". Molecular Reality Corporation. October 2026.