Mineralogical investigations of agates from Cordón de Lila, Chile
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| Formato: | Artículo científico |
| Lenguaje: | en |
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Servicio Nacional de Geología y Minería
2015
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| _version_ | 1876443941770887168 |
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| author | Stefan Richter |
| author_facet | Stefan Richter |
| contents | Mineralogical investigations of agates from Cordón de Lila, Chile Stefan Richter Jens Götze Hans Niemeyer Robert Möckel Ciencias de la Tierra Agate Mineralogy Geochemistry Cordón de Lila Volcanic rocks In the present study a first found of agates in Chile is reported from the Cordón de Lila region in northernChile. The agates occur as veins and lenses in altered Permian volcanic rocks. The rock composition is rhyodacitic/dacitic consisting of a fine-grained K-feldspar-quartz groundmass with phenocrysts of plagioclase (An50-60) and pyroxene(augite). The volcanic host rocks show strong features of alteration and brecciation. Results of XRD, polarizing microscopyand cathodoluminescence (CL) microscopy and spectroscopy point to a late- to postvolcanic formation of the agatesby hydrothermal fluids and SiO2 which was released during the alteration of unstable minerals and volcanic glass.Strongly varying agate micro-textures and the appearance of euhedral quartz crystals with μm-sized growth lamellae(so called Bambauer quartz) indicate fluctuations in the physico-chemical conditions (SiO2 concentration, pH) duringalteration and agate formation. Another indication for the alteration processes is the occurrence of secondary calcite inthe agate-bearing rocks. 2015 artículo científico 0718-7092 https://www.redalyc.org/articulo.oa?id=173941333006 en http://www.redalyc.org/revista.oa?id=1739 Andean Geology application/pdf Servicio Nacional de Geología y Minería Andean Geology (Chile) Num.3 Vol.42 |
| format | Artículo científico |
| id | redalyc_173941333006 |
| institution | Redalyc |
| language | en |
| publishDate | 2015 |
| publisher | Servicio Nacional de Geología y Minería |
| spellingShingle | Mineralogical investigations of agates from Cordón de Lila, Chile Stefan Richter Ciencias de la Tierra Agate Mineralogy Geochemistry Cordón de Lila Volcanic rocks Mineralogical investigations of agates from Cordón de Lila, Chile Stefan Richter Jens Götze Hans Niemeyer Robert Möckel Ciencias de la Tierra Agate Mineralogy Geochemistry Cordón de Lila Volcanic rocks In the present study a first found of agates in Chile is reported from the Cordón de Lila region in northernChile. The agates occur as veins and lenses in altered Permian volcanic rocks. The rock composition is rhyodacitic/dacitic consisting of a fine-grained K-feldspar-quartz groundmass with phenocrysts of plagioclase (An50-60) and pyroxene(augite). The volcanic host rocks show strong features of alteration and brecciation. Results of XRD, polarizing microscopyand cathodoluminescence (CL) microscopy and spectroscopy point to a late- to postvolcanic formation of the agatesby hydrothermal fluids and SiO2 which was released during the alteration of unstable minerals and volcanic glass.Strongly varying agate micro-textures and the appearance of euhedral quartz crystals with μm-sized growth lamellae(so called Bambauer quartz) indicate fluctuations in the physico-chemical conditions (SiO2 concentration, pH) duringalteration and agate formation. Another indication for the alteration processes is the occurrence of secondary calcite inthe agate-bearing rocks. 2015 artículo científico 0718-7092 https://www.redalyc.org/articulo.oa?id=173941333006 en http://www.redalyc.org/revista.oa?id=1739 Andean Geology application/pdf Servicio Nacional de Geología y Minería Andean Geology (Chile) Num.3 Vol.42 |
| title | Mineralogical investigations of agates from Cordón de Lila, Chile |
| topic | Ciencias de la Tierra Agate Mineralogy Geochemistry Cordón de Lila Volcanic rocks |
| url | https://www.redalyc.org/articulo.oa?id=173941333006 |