Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides
Autor(a) principal: | |
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Data de Publicação: | 2015 |
Outros Autores: | , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | REM. Revista Escola de Minas (Online) |
Texto Completo: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000100053 |
Resumo: | Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins. |
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Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guidesorange opalsolid inclusionshydrothermal genesisOrange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.Escola de Minas2015-03-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000100053Rem: Revista Escola de Minas v.68 n.1 2015reponame:REM. Revista Escola de Minas (Online)instname:Escola de Minasinstacron:ESCOLA DE MINAS10.1590/0370-44672015680203info:eu-repo/semantics/openAccessMarques,Gisele TavaresCosta,Marcondes Lima daGomes,Érico Rodrigueseng2015-10-09T00:00:00Zoai:scielo:S0370-44672015000100053Revistahttp://www.scielo.br/remhttps://old.scielo.br/oai/scielo-oai.phpeditor@rem.com.br1807-03530370-4467opendoar:2015-10-09T00:00REM. Revista Escola de Minas (Online) - Escola de Minasfalse |
dc.title.none.fl_str_mv |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
title |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
spellingShingle |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides Marques,Gisele Tavares orange opal solid inclusions hydrothermal genesis |
title_short |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
title_full |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
title_fullStr |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
title_full_unstemmed |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
title_sort |
Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides |
author |
Marques,Gisele Tavares |
author_facet |
Marques,Gisele Tavares Costa,Marcondes Lima da Gomes,Érico Rodrigues |
author_role |
author |
author2 |
Costa,Marcondes Lima da Gomes,Érico Rodrigues |
author2_role |
author author |
dc.contributor.author.fl_str_mv |
Marques,Gisele Tavares Costa,Marcondes Lima da Gomes,Érico Rodrigues |
dc.subject.por.fl_str_mv |
orange opal solid inclusions hydrothermal genesis |
topic |
orange opal solid inclusions hydrothermal genesis |
description |
Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins. |
publishDate |
2015 |
dc.date.none.fl_str_mv |
2015-03-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000100053 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000100053 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/0370-44672015680203 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
dc.publisher.none.fl_str_mv |
Escola de Minas |
publisher.none.fl_str_mv |
Escola de Minas |
dc.source.none.fl_str_mv |
Rem: Revista Escola de Minas v.68 n.1 2015 reponame:REM. Revista Escola de Minas (Online) instname:Escola de Minas instacron:ESCOLA DE MINAS |
instname_str |
Escola de Minas |
instacron_str |
ESCOLA DE MINAS |
institution |
ESCOLA DE MINAS |
reponame_str |
REM. Revista Escola de Minas (Online) |
collection |
REM. Revista Escola de Minas (Online) |
repository.name.fl_str_mv |
REM. Revista Escola de Minas (Online) - Escola de Minas |
repository.mail.fl_str_mv |
editor@rem.com.br |
_version_ |
1754122198984949760 |