Lapis lazuli (/ˈlæpɪs ˈlæzjʊli, -laɪ/), or lapis for short, is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color. Two of the columns framing the iconostasis in St. Isaac's Cathedral in Saint Petersburg are built with lapis. [citation needed], In addition to the Afghan deposits, lapis is also extracted in the Andes (near Ovalle, Chile); and to the west of Lake Baikal in Siberia, Russia, at the Tultui Lazurite deposit. During the height of the Indus Valley Civilisation, approximately 2000 BCE, the Harappan colony, now known as Shortugai, was established near the lapis mines. In his book on stones, the Greek scientist Theophrastus described "the sapphirus, which is speckled with gold," a description which matches lapis lazuli.[26]. Uses of Metamorphic Rocks. A large number of minerals that are usually clear, white, or other colors may be occasionally found in shades from the blue to violet end of the spectrum. https://www.nationalgeographic.org/encyclopedia/metamorphic-rocks Deeply weathered zones, especially those at the top of metal-rich rocks and ore bodies, produce many different oxides and hydrated minerals with strong colors. Smaller quantities are mined in Pakistan, Italy, Mongolia, the United States, and Canada. Blueschist facies is determined by the particular temperature and pressure conditions required to metamorphose basalt to form blueschist. 8. A dagger with a lapis handle, a bowl inlaid with lapis, amulets, beads, and inlays representing eyebrows and beards, were found in the Royal Tombs of the Sumerian city-state of Ur from the 3rd Millennium BCE. Quartz is frequently used in electronic circuitry. Spodumene is the most common source of high-grade lithium. It is widespread in metamorphosed basalts, usually in felted masses of tiny needle-like crystals. Its pyroxene cleavage is combined with a splintery fracture. It is primarily used as a gemstone or for architectural decoration. Contact metamorphism occurs in rock exposed to high temperature and low pressure, as might happen when hot magma intrudes into or lava flows over pre-existing protolith. Apatite is commonly found and is used for fertilizer and pigments. In late classical times and as late as the Middle Ages, lapis lazuli was often called sapphire (sapphirus in Latin, sappir in Hebrew),[25] though it had little to do with the stone today known as the blue corundum variety sapphire. [15] An electronic excitation of one electron from the highest doubly filled molecular orbital (No. Kyanite, the one favored by higher pressure and lower temperature, typically has a mottled, light blue color. The most common blue/bluish minerals of this type include azurite, chalcanthite, chrysocolla, linarite, opal, smithsonite, turquoise, and vivianite. If that isn't enough to identify it, cordierite is commonly associated with mica minerals or chlorite, its alteration products. Important amounts are also produced from mines west of Lake Baikal in Russia, and in the Andes mountains in Chile which is the source that the Inca used to carve artifacts and jewelry from. The most important mineral component of lapis lazuli is lazurite[13] (25% to 40%), a blue feldspathoid silicate mineral with the formula (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2. Each chapter will include a few questions designed to test your knowledge of material covered in the chapter and in the Internet-based resources. There are two major subdivisions of metamorphic rocks. Look for it wherever lithium minerals occur, such as in colored tourmaline or spodumene. What Fossils? 6.4.2: Contact Metamorphism. Lapparent A. F., Bariand, P. et Blaise, J., "Une visite au gisement de lapis lazuli de Sar-e-Sang du Hindu Kouch, Afghanistan," C.R. READ: What is a Biome and What are Major Types of Biomes on Earth? [6][23], Jewelry made of lapis lazuli has also been found at Mycenae attesting to relations between the Myceneans and the developed civilizations of Egypt and the East.[24]. Decide the best name for its color or colors, such as blue-green, sky blue, lilac, indigo, violet, or purple. There are a handful of other blue/bluish minerals that occur in various uncommon settings: anatase (pegmatites and hydrothermal), benitoite (one occurrence worldwide), bornite (bright blue tarnish on a metallic mineral), celestine (in limestones), lazulite (hydrothermal), and the tanzanite variety of zoisite (in jewelry). Ultramarine has also been found in dental tartar of medieval nuns and scribes. 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