This work reports data on lithoid materials, namely travertine and "basaltina" (a local name for a leucite-bearing rock of phonolite-tephrite composition), used to build the apse of the Orvieto Cathedral, in order to recognize the provenance and to study the causes of the deterioration of the stone itself. All the samples underwent analytical surveys and physical tests, to establish their chemical, mineralogical, petrographical, and physical properties. The stone decay observed in the SSE rose-window cannot be explained by chemical causes. Instead, static problems coupled with the effects of thermal stresses, caused by the different thermal and mechanical properties of travertine and "basaltina", could explain the deterioration. Travertine used in the apse of the Orvieto Cathedral does not present any sign of damage. Information about the genetic environment is useful in order to ascertain the geographic provenance of travertines, whereas direct comparison between apse and outcrop material cannot be used, owing to the wide range of variability of their textural and chemical characteristics. On the basis of the presence of the same magmatic component, the provenance of phytothermal and stromatolitic travertines could belong to the "Basalt pyroclastic complex" outcropping in the outskirts of Orvieto. Analyzed travertines could represent succeeding phases in the sedimentary evolution of a lacustrine basin, with stromatolitic travertines lying upon phytothermal travertines.

Lithoid materials from the apse of Orvieto Cathedral (Terni, Italy): deterioration characteristics and provenance

POLI, Giampiero;MORONI, Beatrice;
1992

Abstract

This work reports data on lithoid materials, namely travertine and "basaltina" (a local name for a leucite-bearing rock of phonolite-tephrite composition), used to build the apse of the Orvieto Cathedral, in order to recognize the provenance and to study the causes of the deterioration of the stone itself. All the samples underwent analytical surveys and physical tests, to establish their chemical, mineralogical, petrographical, and physical properties. The stone decay observed in the SSE rose-window cannot be explained by chemical causes. Instead, static problems coupled with the effects of thermal stresses, caused by the different thermal and mechanical properties of travertine and "basaltina", could explain the deterioration. Travertine used in the apse of the Orvieto Cathedral does not present any sign of damage. Information about the genetic environment is useful in order to ascertain the geographic provenance of travertines, whereas direct comparison between apse and outcrop material cannot be used, owing to the wide range of variability of their textural and chemical characteristics. On the basis of the presence of the same magmatic component, the provenance of phytothermal and stromatolitic travertines could belong to the "Basalt pyroclastic complex" outcropping in the outskirts of Orvieto. Analyzed travertines could represent succeeding phases in the sedimentary evolution of a lacustrine basin, with stromatolitic travertines lying upon phytothermal travertines.
1992
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/911366
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