https://www.duncankellergeo.com/publications daily 0.75 2025-08-16 https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/8e8edf0e-5d85-4506-8cc0-e69b66d1a1a5/Mars_cartoon.png https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/d6e9c837-3f89-4912-aeb3-e4dbee77a894/IMG_4363_processed_watermark.png https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/eb79644c-6c01-47de-91f3-94e3b731b3ed/14AD7_processed_crop.png https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/097ae225-4310-40a6-a34d-7c7a50e89108/20171219_132642.jpg https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/a7feae58-7058-432d-83d0-dc71fb7fd694/BIF1-6198_crop.jpg https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1659541884772-LM545Z8FKCAFULIF6PMI/image-asset.png Publications in Brief - Predicting and explaining exsolution behavior Why do exsolved crystalline phases adopt the alignments relative to their hosts that we observe? We examined the crystallography of exsolved rutile, ilmenite, apatite, corundum, and quartz precipitates in garnet and applied a concept from metallurgy called “edge-to-edge matching” that can explain much of the observed behavior. Read about how this concept works, the some promising ways in which it can be applied to retrieve information about a rock’s history, and exciting frontiers for testing it in other mineral systems. https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1638863153778-2CGIUULN53GKBP3VNB16/contamination_image.png Publications in Brief - Recognizing sample contamination Coesite and diamond are the gold-standard indicator minerals for ultrahigh-pressure metamorphism. We document several scenarios from our sample preparation and analysis that run the risk of being misinterpreted as genuine metamorphic coesite and diamond, including contamination from diamond and SiC polishing grit. The full paper is available to subscribers on the NJMA website, linked by the button below. A preprint is available at this link to the preprint repository here on my site. https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1635475023123-XF50U7IHVILF74JFUK3K/JAQ341C-1_core_stack_0002+-+Copy_processed.png Publications in Brief - Ultrahigh-pressure metamorphism during Appalachian orogenesis left fingerprints in garnet Exsolution lamellae of silicates, oxides, and phosphates in garnet reveal metasediment burial to ultrahigh-pressures >5 GPa during the formation of the Appalachian mountains. Return of these extraordinary rocks to the base of the crust shows geochemical recycling of subducted material. Findings have implications for recognizing ultrahigh-pressure rocks using garnet chemistry and for understanding the dynamics of orogenesis. Image: Thin section photomicrograph of quartz, ilmenite, apatite, and rutile exsolution lamellae in garnet, Brimfield Schist, Connecticut, U.S.A. Vertically integrated focus. https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1635785947851-RHP6DJUYG8FITC80N7EQ/IMG_3369_processed.png Publications in Brief - Identifying exsolved phases in garnet using crystallography Common crystallographic traits connect precipitates in garnet from multiple localities and shed light on the factors influencing exsolution in garnet. Similarities between rutile exsolution from garnet and exsolution textures in meteorites open avenues for comparative study. Image: Exsolution textures in Sacramento Mountains iron meteorite, YPM MIN.101193. Courtesy of the Division of Mineralogy & Meteoritics; Peabody Museum of Natural History, Yale University; peabody.yale.edu. Photography by Duncan Keller. https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1635545665946-HU9G5JHOFXIG4K7HRSGR/20170712_155517_processed_crop.png Publications in Brief - Exhumed Appalachian mountain roots in Connecticut Garnet, spinel, and corundum, combined with temperature estimates from ternary feldspars, show that rocks from the New England Appalachians formed at the base of over-thickened crust. Image: Thin section photomicrograph of perthite and antiperthite with other feldspar in thin section from high-pressure granulite, Brimfield Schist, Connecticut, U.S.A. Field of view is ~5.5 mm. https://www.duncankellergeo.com/home daily 1.0 2025-11-20 https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/fc409d96-0164-4d57-96ba-58b2f4568bbf/DSK_headshot_2024.jpg Home - Currently: Visiting Assistant Professor, Skidmore College Dept. of Geosciences I study processes in the crusts and mantles of rocky planets using mineralogical, petrological, and geochemical tools. My work combines in-situ methods (e.g., EPMA, EBSD, LA-ICP-MS) with mineral and bulk rock geochemistry (e.g., major and trace elements, radiogenic and stable isotopes), detailed characterization of thin sections, and numerical modelling. My research includes study of critical mineral deposit formation, early Earth petrology and tectonics, pure and applied mineralogy and crystallography, planetary geology, and relationships between subduction and mantle dynamics. The “Publications in Brief” page gives short descriptions of my papers and links to download them. https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/c5984478-2534-4845-bada-55e59fb28f6c/Lab_logo_2025.png https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/cc032b56-e9f4-4d93-9be3-4b79323cdad9/Orthopyroxene+megacrysts+in+anorthosite%2C+Adirondack+Mountains%2C+NY%2C+USA https://www.duncankellergeo.com/bread daily 0.75 2024-09-02 https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/4421b9f2-5ba0-42d3-bcff-08113c4acd07/Pan_de_cristal_processed.png Bread Pan de cristal https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/22bf114d-25e0-4f33-9b6b-a8c18b896a4d/20240107_231003_processed.png Bread Pain au chocolat https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/9e0001f0-4e60-4c17-98d5-a7e8ca560fb9/20240127_115121_processed.png Bread Sour cream and herb dinner rolls https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/3ef9a6eb-3703-40fa-a098-ed80fd55fa33/IMG_4417_processed.png Bread Country-style boule https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/fcc63ce5-69ea-4d16-9fa7-e31c6ba3be11/IMG_4427_processed.png Bread Country-style boule crumb https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/d9419a2e-8d70-474e-bd40-4f2638d630e1/20241103_211105.png Bread Chocolate babka https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/7f23c38f-21a7-4271-84b3-9a44dbe69c31/20250112_170103_crop.png Bread Everything bagels https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/ee7990ca-be67-4d19-8ac2-46bae3ee990d/20240331_202418_processed.png Bread Cinnamon conchas https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1647066262703-WQWYRDQGXCRO2UMFUCJ7/20220309_161828_processed.png Bread Sandwich buns with flax and sesame seeds https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/bcad2b40-43fc-4edf-8061-755b9e74898f/Walnut_maple_buns_processed_crop.png Bread Walnut and pecan maple buns https://www.duncankellergeo.com/preprints daily 0.75 2024-08-31 https://www.duncankellergeo.com/outreach-and-museums daily 0.75 2025-08-16 https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1659540838479-3J0R69AEUXGSWGNR4YVC/2016_12_09_13-41-46_App_Designers_David_Friend_Hall.jpg Outreach and Museums https://www.duncankellergeo.com/press daily 0.75 2026-03-26 https://www.duncankellergeo.com/science-photos daily 0.75 2025-08-16 https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/2c91a27c-c607-4f95-8b2c-f58bb5dc267c/VHX_000397_processed_watermark.png Science Photos Garnet with exsolved oxides, Garnet Ridge, AZ https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/2b9560c6-4ee0-4d00-a0c2-0d2608204e5c/20251011_111517.jpg Science Photos Big Garnet Amphibolite, Warrensburg, NY, USA https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1725116241002-PBTCEF789EHP2S19LA7L/20220715_154037_processed.jpg Science Photos https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/0d0d54dc-fbdb-4648-a667-40b8ea11e936/20220715_125413.jpg Science Photos Marcy Massif, Adirondack Mountains, NY, USA https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/1635652609971-AKOXHLINAF7SYO21OYHX/20161220_094641.jpg Science Photos Ice, Becker Quarry, Tolland County, CT, USA https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/4f613664-9e39-403e-8d91-f0e422ae13f1/Kochi_folds.jpg Science Photos Folded metacherts, Kochi, Shikoku Island, Japan https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/eb79644c-6c01-47de-91f3-94e3b731b3ed/14AD7_processed_crop.png Science Photos Labradorescent plagioclase under the binocular microscope https://images.squarespace-cdn.com/content/v1/617b20252d96722c71333c61/d6e9c837-3f89-4912-aeb3-e4dbee77a894/IMG_4363_processed_watermark.png Science Photos Almandine garnet in pegmatite, Ishikawa Pegmatite district, Honshu Island, Japan