Cargando…

Garnet, the archetypal cubic mineral, grows tetragonal

Garnet is the archetypal cubic mineral, occurring in a wide variety of rock types in Earth’s crust and upper mantle. Owing to its prevalence, durability and compositional diversity, garnet is used to investigate a broad range of geological processes. Although birefringence is a characteristic featur...

Descripción completa

Detalles Bibliográficos
Autores principales: Cesare, B., Nestola, F., Johnson, T., Mugnaioli, E., Della Ventura, G., Peruzzo, L., Bartoli, O., Viti, C., Erickson, T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6789019/
https://www.ncbi.nlm.nih.gov/pubmed/31605020
http://dx.doi.org/10.1038/s41598-019-51214-9
_version_ 1783458555432534016
author Cesare, B.
Nestola, F.
Johnson, T.
Mugnaioli, E.
Della Ventura, G.
Peruzzo, L.
Bartoli, O.
Viti, C.
Erickson, T.
author_facet Cesare, B.
Nestola, F.
Johnson, T.
Mugnaioli, E.
Della Ventura, G.
Peruzzo, L.
Bartoli, O.
Viti, C.
Erickson, T.
author_sort Cesare, B.
collection PubMed
description Garnet is the archetypal cubic mineral, occurring in a wide variety of rock types in Earth’s crust and upper mantle. Owing to its prevalence, durability and compositional diversity, garnet is used to investigate a broad range of geological processes. Although birefringence is a characteristic feature of rare Ca–Fe(3+) garnet and Ca-rich hydrous garnet, the optical anisotropy that has occasionally been documented in common (that is, anhydrous Ca–Fe(2+)–Mg–Mn) garnet is generally attributed to internal strain of the cubic structure. Here we show that common garnet with a non-cubic (tetragonal) crystal structure is much more widespread than previously thought, occurring in low-temperature, high-pressure metamorphosed basalts (blueschists) from subduction zones and in low-grade metamorphosed mudstones (phyllites and schists) from orogenic belts. Indeed, a non-cubic symmetry appears to be typical of common garnet that forms at low temperatures (<450 °C), where it has a characteristic Fe–Ca-rich composition with very low Mg contents. We propose that, in most cases, garnet does not initially grow cubic. Our discovery indicates that the crystal chemistry and thermodynamic properties of garnet at low-temperature need to be re-assessed, with potential consequences for the application of garnet as an investigative tool in a broad range of geological environments.
format Online
Article
Text
id pubmed-6789019
institution National Center for Biotechnology Information
language English
publishDate 2019
publisher Nature Publishing Group UK
record_format MEDLINE/PubMed
spelling pubmed-67890192019-10-17 Garnet, the archetypal cubic mineral, grows tetragonal Cesare, B. Nestola, F. Johnson, T. Mugnaioli, E. Della Ventura, G. Peruzzo, L. Bartoli, O. Viti, C. Erickson, T. Sci Rep Article Garnet is the archetypal cubic mineral, occurring in a wide variety of rock types in Earth’s crust and upper mantle. Owing to its prevalence, durability and compositional diversity, garnet is used to investigate a broad range of geological processes. Although birefringence is a characteristic feature of rare Ca–Fe(3+) garnet and Ca-rich hydrous garnet, the optical anisotropy that has occasionally been documented in common (that is, anhydrous Ca–Fe(2+)–Mg–Mn) garnet is generally attributed to internal strain of the cubic structure. Here we show that common garnet with a non-cubic (tetragonal) crystal structure is much more widespread than previously thought, occurring in low-temperature, high-pressure metamorphosed basalts (blueschists) from subduction zones and in low-grade metamorphosed mudstones (phyllites and schists) from orogenic belts. Indeed, a non-cubic symmetry appears to be typical of common garnet that forms at low temperatures (<450 °C), where it has a characteristic Fe–Ca-rich composition with very low Mg contents. We propose that, in most cases, garnet does not initially grow cubic. Our discovery indicates that the crystal chemistry and thermodynamic properties of garnet at low-temperature need to be re-assessed, with potential consequences for the application of garnet as an investigative tool in a broad range of geological environments. Nature Publishing Group UK 2019-10-11 /pmc/articles/PMC6789019/ /pubmed/31605020 http://dx.doi.org/10.1038/s41598-019-51214-9 Text en © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Cesare, B.
Nestola, F.
Johnson, T.
Mugnaioli, E.
Della Ventura, G.
Peruzzo, L.
Bartoli, O.
Viti, C.
Erickson, T.
Garnet, the archetypal cubic mineral, grows tetragonal
title Garnet, the archetypal cubic mineral, grows tetragonal
title_full Garnet, the archetypal cubic mineral, grows tetragonal
title_fullStr Garnet, the archetypal cubic mineral, grows tetragonal
title_full_unstemmed Garnet, the archetypal cubic mineral, grows tetragonal
title_short Garnet, the archetypal cubic mineral, grows tetragonal
title_sort garnet, the archetypal cubic mineral, grows tetragonal
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6789019/
https://www.ncbi.nlm.nih.gov/pubmed/31605020
http://dx.doi.org/10.1038/s41598-019-51214-9
work_keys_str_mv AT cesareb garnetthearchetypalcubicmineralgrowstetragonal
AT nestolaf garnetthearchetypalcubicmineralgrowstetragonal
AT johnsont garnetthearchetypalcubicmineralgrowstetragonal
AT mugnaiolie garnetthearchetypalcubicmineralgrowstetragonal
AT dellaventurag garnetthearchetypalcubicmineralgrowstetragonal
AT peruzzol garnetthearchetypalcubicmineralgrowstetragonal
AT bartolio garnetthearchetypalcubicmineralgrowstetragonal
AT vitic garnetthearchetypalcubicmineralgrowstetragonal
AT ericksont garnetthearchetypalcubicmineralgrowstetragonal