Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India
This work reports calcium oxalate film formation on basaltic stone surfaces of the 17th-century western India Raigad Hill Fort. Nine stone samples extracted from the exterior surfaces of different historical structures of the fort were investigated under FTIR, optical microscopy, XRD, and SEM-EDX. T...
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MDPI AG
2023-07-01
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| Series: | Heritage |
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| Online Access: | https://www.mdpi.com/2571-9408/6/7/283 |
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| author | Manager Rajdeo Singh Rajendra Yadav |
| author_facet | Manager Rajdeo Singh Rajendra Yadav |
| author_sort | Manager Rajdeo Singh |
| collection | DOAJ |
| description | This work reports calcium oxalate film formation on basaltic stone surfaces of the 17th-century western India Raigad Hill Fort. Nine stone samples extracted from the exterior surfaces of different historical structures of the fort were investigated under FTIR, optical microscopy, XRD, and SEM-EDX. The FTIR spectroscopy revealed intense peaks for Ca-oxalate patinas on basaltic stone surfaces. Observation under optical microscopy clearly showed milky white oxalate films, and peaks for crystalline calcium oxalate, including rock silicates, were prominently observed through XRD investigations. The surface morphology, the origin of the oxalate film, and the state of conservation of the basalt rock were investigated through SEM-EDX. The massive structures at Raigad, at a height of about 800 m, have hardly been chemically cleaned or coated with preservatives in the past. The presence of organic filaments in SEM photomicrographs indicated the biological origin of the oxalate patina due to the thick growth of microbiota on the monument stone during very heavy monsoons. The oxalic acid secreted by microbes dislodged the Ca-rich plagioclase of the stone, ensuring Ca-ions’ availability for film formation. The optical and mineralogical analyses suggest that the film is not the result of simple deposition but of the surface transformation of basaltic stone. |
| first_indexed | 2024-03-11T01:02:12Z |
| format | Article |
| id | doaj.art-ed9a1ce33a334b4b8d1f4d8e6e06671a |
| institution | Directory Open Access Journal |
| issn | 2571-9408 |
| language | English |
| last_indexed | 2024-03-11T01:02:12Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Heritage |
| spelling | doaj.art-ed9a1ce33a334b4b8d1f4d8e6e06671a2023-11-18T19:34:39ZengMDPI AGHeritage2571-94082023-07-01675374539210.3390/heritage6070283Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, IndiaManager Rajdeo Singh0Rajendra Yadav1Research Associate, Department of Tourism Administration, Dr. Babasaheb Ambedkar Marathwada University, Chhatrapati Sambhaji Nagar 431004, IndiaArcheological Survey of India, Sion Fort, Mumbai 400022, IndiaThis work reports calcium oxalate film formation on basaltic stone surfaces of the 17th-century western India Raigad Hill Fort. Nine stone samples extracted from the exterior surfaces of different historical structures of the fort were investigated under FTIR, optical microscopy, XRD, and SEM-EDX. The FTIR spectroscopy revealed intense peaks for Ca-oxalate patinas on basaltic stone surfaces. Observation under optical microscopy clearly showed milky white oxalate films, and peaks for crystalline calcium oxalate, including rock silicates, were prominently observed through XRD investigations. The surface morphology, the origin of the oxalate film, and the state of conservation of the basalt rock were investigated through SEM-EDX. The massive structures at Raigad, at a height of about 800 m, have hardly been chemically cleaned or coated with preservatives in the past. The presence of organic filaments in SEM photomicrographs indicated the biological origin of the oxalate patina due to the thick growth of microbiota on the monument stone during very heavy monsoons. The oxalic acid secreted by microbes dislodged the Ca-rich plagioclase of the stone, ensuring Ca-ions’ availability for film formation. The optical and mineralogical analyses suggest that the film is not the result of simple deposition but of the surface transformation of basaltic stone.https://www.mdpi.com/2571-9408/6/7/283calcium oxalatebio-mineralizationSEM-EDXmorphologymineralogybasalt stone |
| spellingShingle | Manager Rajdeo Singh Rajendra Yadav Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India Heritage calcium oxalate bio-mineralization SEM-EDX morphology mineralogy basalt stone |
| title | Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India |
| title_full | Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India |
| title_fullStr | Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India |
| title_full_unstemmed | Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India |
| title_short | Formation of Calcium Oxalate Patinas as Protective Layer on Basaltic Stone Surfaces of 17th Century Raigad Hill Fort, India |
| title_sort | formation of calcium oxalate patinas as protective layer on basaltic stone surfaces of 17th century raigad hill fort india |
| topic | calcium oxalate bio-mineralization SEM-EDX morphology mineralogy basalt stone |
| url | https://www.mdpi.com/2571-9408/6/7/283 |
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