For the community in the United States, seeDiorite, Michigan. For the nuclear research reactor in Switzerland, seeDIORIT.
DioriteOrbicular diorite from Corsica (corsite)QAPF diagram with dioritoid fields highlighted in yellow and diorite in redMineral assemblage of igneous rocks
Diorite is found in mountain-building belts (orogens) on the margins of continents. It has the same composition as the fine-grained volcanic rock,andesite, which is also common in orogens.
Diorite has been used since prehistoric times as decorative stone. It was used by theAkkadian Empire ofSargon of Akkad for funerary sculptures, and by many later civilizations for sculptures and building stone.
Geologists use rigorous quantitative definitions to classify coarse-grained igneous rocks, based on the mineral content of the rock. For igneous rocks composed mostly of silicate minerals, and in which at least 10% of the mineral content consists ofquartz, feldspar, orfeldspathoid minerals, classification begins with theQAPF diagram. The relative abundances of quartz (Q),alkali feldspar (A), plagioclase (P), and feldspathoid (F), are used to plot the position of the rock on the diagram.[5][6][7] The rock will be classified as either adioritoid or agabbroid if quartz makes up less than 20% of the QAPF content, feldspathoid makes up less than 10% of the QAPF content, and plagioclase makes up more than 65% of the total feldspar content. Dioritoids are distinguished from gabbroids by ananorthite (calcium plagioclase) fraction of their total plagioclase of less than 50%.[8]
The composition of the plagioclase cannot easily be determinedin the field, and then a preliminary distinction is made between dioritoid and gabbroid based on the content of mafic minerals. A dioritoid typically has less than 35% mafic minerals, typically including hornblende, while a gabbroid typically has over 35% mafic minerals, mostly pyroxenes or olivine.[9] The namediorite (fromAncient Greekδιορίζειν, "to distinguish") was first applied to the rock byRené Just Haüy[10] on account of its characteristic, easily identifiable large crystals of hornblende.[4]
Dioritoids form a family of rock types similar to diorite, such asmonzodiorite,quartz diorite, ornepheline-bearing diorite. Diorite itself is more narrowly defined, as a dioritoid in which quartz makes up less than 5% of the QAPF content, feldspathoids are not present, and plagioclase makes up more than 90% of the feldspar content.[11][5][6]
Coarse-grained (phaneritic) dioritoids are produced by slow crystallization ofmagma having the same composition as thelava that solidifies rapidly to form fine-grained (aphanitic)andesite.[5][6] Rock of similar composition to diorite or andesite but with an intermediate texture is sometimes calledmicrodiorite.[16] Diorite is occasionallyporphyritic.[17] It usually contains enough mafic minerals to be dark in appearance.[18]Orbicular diorite shows alternating concentric growth bands of plagioclase andamphibole surrounding a nucleus, within a dioriteporphyrymatrix.[19]
Anorbicular variety found inCorsica was formerly calledcorsite.[33] An obsolete name for microdiorite,markfieldite, was given by Frederick Henry Hatch in 1909 to exposures near the village ofMarkfield, England.[34]Esterellite is a local name for microdiorite given byAuguste Michel-Lévy to exposures in the Esterel Massif in France.[35]
Human use of diorite dates at least to theMiddle Neolithic, when it was used in apassage grave at Le Dolmen du Mont Ubé,Jersey. The use of stone of contrasting colour suggests that diorite was deliberately selected for its appearance.[36]
The first greatMesopotamian empire, theAkkadian Empire ofSargon of Akkad, began using diorite for sculpture after sources of the rock came under Akkadian control. Diorite was used to depict rulers or high officials in ceremonial poses or attitudes of prayer, and the sculptures may have been designed to receive funerary offerings.[37] Diorite was also used for stone vases byBronze Age craftspeople, who developed considerable skill at polishing diorite and other stones.[38] The Egyptians had become skilled at shaping diorite and other hard stones by 4000 BCE.[39] A large dioritestela in theLouvre Museum dating to 1700 BCE is inscribed with theCode of Hammurabi.[40]
Diorite was used by theInca[41] civilization as structural stone. It was used by medieval Islamic builders to construct water fountains in theCrimea.[42] In later times, diorite was commonly used ascobblestone; today many diorite cobblestone streets can be found in England and Guernsey.[43] Guernsey diorite was used in the steps ofSt Paul's Cathedral, London.[44]
Today, diorite is uncommon in construction, although it shares similar physical properties with granite. Diorite is often sold commercially as "black granite".[45] Diorite's modern uses includeconstruction aggregate, curbing, usage asdimension stones, cobblestone, and facing stones.
Head of a cow goddess (Hathor orMehet-Weret); 1390-1352 BC; height: 53.6 cm (21.1 in), width: 28 cm (11 in), depth: 33 cm (13 in);Metropolitan Museum of Art (New York City)
Statue ofAmun; 1336-1327 BC; height: 220 cm (87 in), width: 44[clarification needed], length: 78 cm (31 in); Louvre
Block statue of the god's father Pameniuwedja, son of Nesmin and Nestefnut; 4th century BC; height: 34.6 cm (13.6 in), width: 14.5 cm (5.7 in), depth: 19.1 cm (7.5 in); Metropolitan Museum of Art
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^abPhilpotts, Anthony R.; Ague, Jay J. (2009).Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 139–143.ISBN978-0-521-88006-0.
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^Allaby, Michael (2013).A dictionary of geology and earth sciences (Fourth ed.). Oxford: Oxford University Press.ISBN9780199653065.
^Cao, Kang; Yang, Zhi-Ming; White, Noel C.; Hou, Zeng-Qian (1 January 2022). "Generation of the Giant Porphyry Cu-Au Deposit by Repeated Recharge of Mafic Magmas at Pulang in Eastern Tibet".Economic Geology.117 (1):57–90.Bibcode:2022EcGeo.117...57C.doi:10.5382/econgeo.4860.S2CID240591656.
^Klein, Cornelis; Hurlbut, Cornelius S. Jr. (1993).Manual of mineralogy : (after James D. Dana) (21st ed.). New York: Wiley.ISBN047157452X.
^Zeming, Zhang; Hua, Xiang; Huixia, Ding; Xin, Dong; Zhengbin, Gou; Zhulin, Tian; Santosh, M. (July 2017). "Miocene orbicular diorite in east-central Himalaya: Anatexis, melt mixing, and fractional crystallization of the Greater Himalayan Sequence".Geological Society of America Bulletin.129 (7–8):869–885.Bibcode:2017GSAB..129..869Z.doi:10.1130/B31586.1.
^Rice, C. M.; Ashcroft, W. A. (December 2003). "The geology of the northern half of the Rhynie Basin, Aberdeenshire, Scotland".Transactions of the Royal Society of Edinburgh: Earth Sciences.94 (4):299–308.doi:10.1017/S0263593300000705.S2CID129097226.
^Käpyaho, A. (2006). "Whole-rock geochemistry of some tonalite and high Mg/Fe gabbro, diorite, and granodiorite plutons (sanukitoid suites) in the Kuhmo district, eastern Finland".Bulletin of the Geological Society of Finland.78 (1–2):121–141.CiteSeerX10.1.1.535.8890.doi:10.17741/bgsf/78.2.002.
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^Harlov, Daniel; Ballouard, Christophe; Elburg, Marlina; Knoper, Michael; Wilke, Franziska; Ning, Wen Bin; Andreoli, Marco A.G. (December 2020). "Genesis of monazite-rich, orthopyroxene-bearing veins in the Kliphoog area of the Concordia Granite, Springbok, Namaqualand, South Africa: Sources, fluids, and the mobility of actinides and REE".Lithos.376–377: 105762.Bibcode:2020Litho.37605762H.doi:10.1016/j.lithos.2020.105762.S2CID225003517.
^Fillmore, Robert (2010).Geological evolution of the Colorado Plateau of eastern Utah and western Colorado, including the San Juan River, Natural Bridges, Canyonlands, Arches, and the Book Cliffs. Salt Lake City: University of Utah Press. pp. 288–295.ISBN9781607810049.
^Bukach, David (February 2003). "Exploring Identity and Place: An Analysis of the Provenance of Passage Grave Stones on Guernsey and Jersey in the Middle Neolithic".Oxford Journal of Archaeology.22 (1):23–33.doi:10.1111/1468-0092.00002.
^Foster, Benjamin R. (2015).Age of Agade. Taylor and Francis. pp. 9, 119.ISBN9781317415527.
^Procopiou, H.; Morero, E.; Vargiolu, R.; Suarez-Sanabria, M.; Zahouani, H. (April 2013). "Tactile and visual perception during polishing: An ethnoarchaeological study in India (Mahabalipuram, Tamil Nadu)".Wear.301 (1–2):144–149.doi:10.1016/j.wear.2012.11.058.
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