{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/74501"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/74501","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Pyrite porphyroblast paragenesis at the Cherokee Mine, Ducktown, Tennessee","abstract":"Pyrite porphyroblasts up to 300 mm in size are common in the polymetamorphosed, iron-rich, stratabound, massive sulfide ore at the Cherokee Mine, Ducktown, Tennessee. These porphyroblasts contain abundant inclusions of sphalerite, calcite, and micas that are used to determine the paragenesis of the porphyroblasts and the metamorphic history of the ore deposit. The ore mineralogy at the mine is: hexagonal pyrrhotite (60%), pyrite (30%), chalcopyrite (4%), sphalerite (3 %), and magnetite (3 %) with minor galena, molybdenum, tetrahedrite, bismuth, ilmenite, and rutile. The ore body is interpreted to have been syngenetic and to have contained both primary pyrrhotite and primary pyrite: additional pyrite may have formed as crusty accretions resulting from oxidation of primary pyrrhotite shortly after deposition. The early pyrites were later deformed and acted as seeds for the formation of the larger porphyroblasts by Ostwald ripening, and by the annealing of small pyrite grains into larger porphyroblasts, during isochemical metamorphism. Sphalerite geobarometry indicates initial growth of the pyrite porphyroblasts began at 6.8± 0.8 kilobars and that many sphalerite grains underwent some degree of re-equilibration at a later stage. Fluid inclusions formed during retrograde metamorphism have salinities near 12 % NaCl with a vapor phase rich in CO₂. Pyrrhotite-pyrite compositional profiles indicate at least partial re-equilibration of hexagonal pyrrhotite down to about 270°C. At lower temperatures further compositional re-equilibration was probably prevented, because the coexisting pyrite was too refractory to release the sulfur needed for the hexagonal pyrrhotite to react to monoclinic pyrrhotite.","abstract_html":"Pyrite porphyroblasts up to 300 mm in size are common in the polymetamorphosed, iron-rich, stratabound, massive sulfide ore at the Cherokee Mine, Ducktown, Tennessee. These porphyroblasts contain abundant inclusions of sphalerite, calcite, and micas that are used to determine the paragenesis of the porphyroblasts and the metamorphic history of the ore deposit. The ore mineralogy at the mine is: hexagonal pyrrhotite (60%), pyrite (30%), chalcopyrite (4%), sphalerite (3 %), and magnetite (3 %) with minor galena, molybdenum, tetrahedrite, bismuth, ilmenite, and rutile. The ore body is interpreted to have been syngenetic and to have contained both primary pyrrhotite and primary pyrite: additional pyrite may have formed as crusty accretions resulting from oxidation of primary pyrrhotite shortly after deposition. The early pyrites were later deformed and acted as seeds for the formation of the larger porphyroblasts by Ostwald ripening, and by the annealing of small pyrite grains into larger porphyroblasts, during isochemical metamorphism. Sphalerite geobarometry indicates initial growth of the pyrite porphyroblasts began at 6.8± 0.8 kilobars and that many sphalerite grains underwent some degree of re-equilibration at a later stage. Fluid inclusions formed during retrograde metamorphism have salinities near 12 % NaCl with a vapor phase rich in CO₂. Pyrrhotite-pyrite compositional profiles indicate at least partial re-equilibration of hexagonal pyrrhotite down to about 270°C. At lower temperatures further compositional re-equilibration was probably prevented, because the coexisting pyrite was too refractory to release the sulfur needed for the hexagonal pyrrhotite to react to monoclinic pyrrhotite.","abstract_has_math":false,"creators":["Brooker, Donald Duane"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Geology","degree_department":"Geology","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1984,"date_issued":"1984","date_published":"1984","updated_at":"2026-07-22T22:19:59Z","subjects":[],"languages":["en_US"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/74501","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Geology"]},{"key":"dc:creator","label":"Author","values":["Brooker, Donald Duane"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-01-30T21:02:35Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-01-30T21:02:35Z"]},{"key":"dc:date.issued","label":"Date","values":["1984"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/74501"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Pyrite porphyroblasts up to 300 mm in size are common in the polymetamorphosed, iron-rich, stratabound, massive sulfide ore at the Cherokee Mine, Ducktown, Tennessee. These porphyroblasts contain abundant inclusions of sphalerite, calcite, and micas that are used to determine the paragenesis of the porphyroblasts and the metamorphic history of the ore deposit. The ore mineralogy at the mine is: hexagonal pyrrhotite (60%), pyrite (30%), chalcopyrite (4%), sphalerite (3 %), and magnetite (3 %) with minor galena, molybdenum, tetrahedrite, bismuth, ilmenite, and rutile. The ore body is interpreted to have been syngenetic and to have contained both primary pyrrhotite and primary pyrite: additional pyrite may have formed as crusty accretions resulting from oxidation of primary pyrrhotite shortly after deposition. The early pyrites were later deformed and acted as seeds for the formation of the larger porphyroblasts by Ostwald ripening, and by the annealing of small pyrite grains into larger porphyroblasts, during isochemical metamorphism. Sphalerite geobarometry indicates initial growth of the pyrite porphyroblasts began at 6.8± 0.8 kilobars and that many sphalerite grains underwent some degree of re-equilibration at a later stage. Fluid inclusions formed during retrograde metamorphism have salinities near 12 % NaCl with a vapor phase rich in CO₂. Pyrrhotite-pyrite compositional profiles indicate at least partial re-equilibration of hexagonal pyrrhotite down to about 270°C. At lower temperatures further compositional re-equilibration was probably prevented, because the coexisting pyrite was too refractory to release the sulfur needed for the hexagonal pyrrhotite to react to monoclinic pyrrhotite."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Pyrite porphyroblast paragenesis at the Cherokee Mine, Ducktown, Tennessee"]}]}],"canonical_facts":{"dc:contributor.department":["Geology"],"dc:creator":["Brooker, Donald Duane"],"dc:date.accessioned":["2017-01-30T21:02:35Z"],"dc:date.available":["2017-01-30T21:02:35Z"],"dc:date.issued":["1984"],"dc:description.abstract":["Pyrite porphyroblasts up to 300 mm in size are common in the polymetamorphosed, iron-rich, stratabound, massive sulfide ore at the Cherokee Mine, Ducktown, Tennessee. These porphyroblasts contain abundant inclusions of sphalerite, calcite, and micas that are used to determine the paragenesis of the porphyroblasts and the metamorphic history of the ore deposit. The ore mineralogy at the mine is: hexagonal pyrrhotite (60%), pyrite (30%), chalcopyrite (4%), sphalerite (3 %), and magnetite (3 %) with minor galena, molybdenum, tetrahedrite, bismuth, ilmenite, and rutile. The ore body is interpreted to have been syngenetic and to have contained both primary pyrrhotite and primary pyrite: additional pyrite may have formed as crusty accretions resulting from oxidation of primary pyrrhotite shortly after deposition. The early pyrites were later deformed and acted as seeds for the formation of the larger porphyroblasts by Ostwald ripening, and by the annealing of small pyrite grains into larger porphyroblasts, during isochemical metamorphism. Sphalerite geobarometry indicates initial growth of the pyrite porphyroblasts began at 6.8± 0.8 kilobars and that many sphalerite grains underwent some degree of re-equilibration at a later stage. Fluid inclusions formed during retrograde metamorphism have salinities near 12 % NaCl with a vapor phase rich in CO₂. Pyrrhotite-pyrite compositional profiles indicate at least partial re-equilibration of hexagonal pyrrhotite down to about 270°C. At lower temperatures further compositional re-equilibration was probably prevented, because the coexisting pyrite was too refractory to release the sulfur needed for the hexagonal pyrrhotite to react to monoclinic pyrrhotite."],"dc:description.degree":["Master of Science"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/74501"],"dc:language.iso":["en_US"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Pyrite porphyroblast paragenesis at the Cherokee Mine, Ducktown, Tennessee"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:59Z"}