Editing Duke University (section)

=== Duke stone ===
[[File:DukeStone1.jpg|thumb|Duke stone showing orange faces (likely iron oxide) at a right angle]]
[[File:DukeStone2.jpg|thumb|Fractured Duke stone showing phyllitic texture]]

The distinctive stone used for [[Duke University West Campus|West Campus]] and other Duke buildings is said to have seven primary colors and seventeen shades of color.<ref>{{cite book |url=https://cap-press.com/books/isbn/9780890898147/If-Gargoyles-Could-Talk |title=If Gargoyles Could Talk: Sketches of Duke University |isbn=9780890898147 |first=William E. |last=King |publisher=Carolina Academic Press |date=1997}}{{page needed|date=May 2023}}</ref><ref>{{cite web |url=https://blogs.library.duke.edu/rubenstein/2013/07/29/faux-duke-stone/ |title=Faux Duke Stone |website=The Devil's Tale |last=McDonald |first=Amy |publisher=Duke University Libraries |date=July 29, 2013}}</ref><ref>{{Cite thesis |title=The Value of a College Degree in a Recession |last=Tricoli |first=Christen |date=April 1, 2011 |degree=Bachelor of Arts |publisher=Duke University |url=https://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/3724/christenTricoliThesisFinal.pdf |access-date=March 29, 2023 |archive-date=April 10, 2023 |archive-url=https://web.archive.org/web/20230410020121/https://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/3724/christenTricoliThesisFinal.pdf |url-status=dead }}</ref> The use of Duke stone has been given partial credit for the university's success: "Duke in fact became a great university in part because it looked like one from the start".<ref name="Duke University">{{cite web |url=https://facilities.duke.edu/campus/architecture |title=Duke's Architecture |publisher=Duke University |access-date=May 11, 2023 |archive-date=March 28, 2023 |archive-url=https://web.archive.org/web/20230328141622/https://facilities.duke.edu/campus/architecture |url-status=dead }}</ref>

During the planning of the [[Collegiate Gothic]] buildings,<ref name="Duke University" /> [[James Buchanan Duke|James B. Duke]] initially suggested the use of stone from the [[Princeton, New Jersey|Princeton]] quarry, but the plans were later amended to purchase a local quarry in [[Hillsborough, North Carolina|Hillsborough]] to reduce costs.<ref name="DukeStone">{{cite web |last=King |first=William E. |url=http://library.duke.edu/uarchives/ |title=DukeStone |url-status=dead |archive-url=https://web.archive.org/web/20080301105243/http://library.duke.edu/uarchives/ |archive-date=March 1, 2008 |work=Duke University Historical Notes |access-date=January 12, 2011}}</ref> After a search for a locally sourced stone suitable for construction in a style "that made it look like the university was growing out of the ground, like it had been here forever,"<ref>{{cite web |url=https://today.duke.edu/2018/06/duke-stone-quarry-campus |title=Duke Stone: From Quarry to Campus |work=Duke Today |last=Schramm |first=Stephen |date=June 18, 2018 |access-date=May 11, 2023}}</ref> Duke stone and its source quarry in [[Hillsborough, North Carolina|Hillsborough]] were identified by Duke University Comptroller [[Frank Clyde Brown]] and purchased by the university in 1925.<ref>{{cite web |url=https://openorangenc.org/content/duke-quarry-new-quarry |title=Duke Quarry / New Quarry |work=Open Orange |access-date=May 11, 2023}}</ref> Comptroller Brown, who oversaw the planning and construction of the Gothic buildings, wrote that Duke stone "is much warmer and softer in coloring than the Princeton, and it will look very much older and have a much more attractive antique effect."<ref>{{cite web |url=https://storymaps.arcgis.com/stories/963b921aeb99473292f69f18397a2a16 |title=Duke's Inspiration from other Institutions |last=Marr |first=Kayla |date=April 16, 2020 |access-date=May 11, 2023}}</ref>

Duke stone is a type of Carolina 'slate' or 'bluestone', a metamorphic [[phyllite]] rock,<ref>{{Cite web |url=https://www.facebook.com/dukeforest/videos/duke-stone-a-story-in-stone/932614984155038/|title=Duke Stone: A Story in Stone &#124; We have just uncovered this 2002 video telling the history of the famous Duke stone, which comes from a quarry in the Duke Forest. The video features an... &#124; By Duke Forest &#124; Facebook |website=Facebook.com}}</ref> with  both [[andesite]] and [[dacite]] mineral composition.<ref name="Allen-1968">{{citation |url=https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Geological%20Survey/Bulletins_NCGS/NCGS_Bulletin_81_Geology_OrangeCounty.pdf |title=Geology and Mineral Resources of Orange County, North Carolina |last1=Allen |first1=Eldon P. |last2=Wilson |first2=William F. |publisher=North Carolina Department of Conservation and Development |date=1968 |location=Raleigh, North Carolina |issue=Bulletin 81 |access-date=March 26, 2023 |archive-date=April 22, 2023 |archive-url=https://web.archive.org/web/20230422003148/https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Geological%20Survey/Bulletins_NCGS/NCGS_Bulletin_81_Geology_OrangeCounty.pdf |url-status=dead }}</ref> Dacitic phyllite is a predominant type of rock found through the Carolina Slate Belt.<ref name="Rogers">{{cite web |last1=Rogers |first1=John |title=The Carolina Slate Belt |url=https://rla.unc.edu/Publications/pdf/ResRep25/Ch2.pdf |website=Archaeology University of North Carolina at Chapel Hill}}</ref> Duke stone and the Carolina Slate Belt, like the greater [[Carolina terrane|Carolina Terrane]],<ref>{{cite web |url=https://deq.nc.gov/about/divisions/energy-mineral-and-land-resources/north-carolina-geological-survey/geologic-hazards/expansive-soils-shrink-swell-clays |title=Expansive soils (shrink swell clays) |publisher=North Carolina Environmental Quality |access-date=May 11, 2023}}</ref> are thought to have formed in the [[Iapetus Ocean]] off the coast of [[Gondwana]] by a chain of volcanic islands known as 'Carolinia',<ref name="Earth@Home.org">{{cite web |url=https://earthathome.org/hoe/se/geologic-history/ |title=Geologic History of the Southeastern United States |website=Earth@Home.org |access-date=May 11, 2023}}</ref> starting around 650 million years ago.<ref name="Rogers"/><ref name="Volcanoes">{{cite encyclopedia |url=https://www.ncpedia.org/volcanoes |title=Volcanoes |encyclopedia=NCpedia |access-date=May 11, 2023}}</ref>

The Carolina Slate Belt contains stone of both meta-volcanic and meta-sedimentary origin.<ref>{{cite encyclopedia |url=https://www.ncpedia.org/slate-belt |title=Slate Belt |encyclopedia=NCpedia |access-date=May 11, 2023}}</ref><ref name="Secor-1983">{{cite journal |url=https://www.science.org/doi/abs/10.1126/science.221.4611.649 |doi=10.1126/science.221.4611.649 |title=Confirmation of the Carolina Slate Belt as an Exotic Terrane |year=1983 |last1=Secor |first1=Donald T. |last2=Samson |first2=Sara L. |last3=Snoke |first3=Arthur W. |last4=Palmer |first4=Allison R. |journal=Science |volume=221 |issue=4611 |pages=649–651 |pmid=17787733 |bibcode=1983Sci...221..649S |s2cid=12942747|issn=0036-8075 }}</ref> The geological literature finds the pre-metamorphosis origin of Duke stone to be variously volcanic and sedimentary: it was likely originally formed by sedimentation of volcanic material.<ref name="Volcanoes" /> A [[USGS]] geologist concludes: "The Duke quarry phyllite was derived from argillite, tuff or tuffaceous sandstone, and volcanic [[breccia]]. Occurrence of laminated argillites suggests marine deposition. … There is insufficient evidence to determine if the volcanic material was deposited directly by igneous action or if it was re-worked by sedimentary processes. Presence of lava flows and very coarse breccias in Orange County suggest that the volcanic centers were relatively near."<ref>{{cite web |location=Raleigh |date=1964 |title=Road Log of the Chatham, Randolph and Orange County Areas, North Carolina |publisher=Carolina Geological Society |url=https://carolinageologicalsociety.org/1960s_files/gb%201964.pdf}}</ref><ref name="Allen-1968" /> A [[University of North Carolina at Chapel Hill|UNC]] geologist concurred that "original features of the phyllite have been obscured by deformation and recrystallization, but the rock apparently was derived from argillites and tuffs," and that "sedimentary reworking of volcanic materials is to be expected."<ref>{{cite web |url=https://libres.uncg.edu/ir/asu/f/SoutheasternGeology_Vol04_No03_1963.pdf |title=Southeastern Geology |volume=4 |number=3 |date=February 1963 |editor-last=Heron Jr. |editor-first=S. Duncan}}</ref>

After its initial formation, Duke stone underwent several metamorphic events, including the collision of [[Carolina terrane|Carolinia]] with [[Laurentia]].<ref name="Hibbard-2002">{{cite journal |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825201000794 |doi=10.1016/S0012-8252(01)00079-4 |title=The Carolina Zone: Overview of Neoproterozoic to Early Paleozoic peri-Gondwanan terranes along the eastern Flank of the southern Appalachians |year=2002 |last1=Hibbard |first1=J. |journal=Earth-Science Reviews |volume=57 |issue=3–4 |pages=299–339 |bibcode=2002ESRv...57..299H}}</ref> The Carolinia-Laurentia collision started around 375 Mya, which coincides with timing of the [[Acadian orogeny]] that formed the [[Appalachian Mountains]]. Though Duke stone contains no fossils, other areas of the Carolina Terrane contain fossilized corals and trilobites that were used to establish that this formation is exotic to the main North American ([[Laurentia]]) landmass.<ref name="Earth@Home.org" /><ref name="Secor-1983" /><ref name="Hibbard-2002" />

The Duke stone quarry now occupies a {{convert|5|acre|adj=on|spell=in}} section of the Hillsboro Division of the Duke Forest.<ref>{{cite web |url=https://dukeforest.spotlight.duke.edu/ |title=11 Interesting Facts About the Duke Forest |publisher=Duke Forest |access-date=May 11, 2023}}</ref> In new construction and repairs on Duke campus, the use of Duke stone is strictly regulated: "All stones shall be laid on their natural beds, with 20 percent of stone being split face and 80 percent seam face, mixed proportionately to show variations of stone coloring".<ref>{{cite web |title=Duke University Construction Standards |url=https://facilities.duke.edu/sites/default/files/04%2040%2000_Duke%20Stone%20Assemblies.pdf |website=Duke Facilities |publisher=Duke University |access-date=March 28, 2023 |archive-date=March 28, 2023 |archive-url=https://web.archive.org/web/20230328142321/https://facilities.duke.edu/sites/default/files/04%2040%2000_Duke%20Stone%20Assemblies.pdf |url-status=dead }}</ref> In recent years, high cost of quarrying the stone, and the irregular [[Knapping|knapped]] [[ashlar]] shapes with its associated high stonemasonry costs has led to the university establishing a mix of bricks to imitate the Duke stone colors.<ref name="Duke University" />