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Title: The Crystal Structures, Solid Solutions and Infrared Spectra of Copiapite-Group Minerals

Abstract

Copiapite is a mineral of iron- and sulphate-rich acidic environments and has a general formula AFe43+(SO4)6(OH)2(H2O)20, where A = Fe2+, 2/3Fe3+, 2/3Al3+, Mg, Zn. The structure is built by infinite tetrahedral-octahedral chains and isolated octahedrally coordinated A sites. Our synthetic and natural copiapite samples can be divided into two large groups based on the orientation of the structural fragments. One group comprises copiapite phases where A = Al3+, Fe2+ or Fe3+ and we designate it as the structural type AL. The other group consists of copiapite with A = Mg2+, Zn2+ or Ni2+ and this is the structural type MG. The solid-solution series between Fe3+ and Al3+ copiapite is continuous. The series between Mg2+-Al3+, Mg2+-Fe3+ and Mg2+-Al3+-Fe3+ copiapite are not continuous; the samples with intermediate compositions contain two copiapite phases, one of the type AL and one of the type MG. The series between Mg2+ and Zn2+ copiapite is continuous only at 25 C. At 75 C, the Zn-rich portion of this system crystallizes a copiapite-like phase whose structure may be a superstructure of copiapite. The series between Al-Fe2+ and Mg-Fe2+ copiapite are not continuous and show complex behaviour of the intermediate compositions.

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
960035
Report Number(s):
BNL-83021-2009-JA
Journal ID: ISSN 0026-461X; MNLMBB; TRN: US201016%%1179
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Mineralogical Magazine; Journal Volume: 71; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHAINS; CRYSTAL STRUCTURE; INFRARED SPECTRA; IRON; ORIENTATION; SOLID SOLUTIONS; national synchrotron light source

Citation Formats

Majzlan,J., and Michallik, R. The Crystal Structures, Solid Solutions and Infrared Spectra of Copiapite-Group Minerals. United States: N. p., 2007. Web. doi:10.1180/minmag.2007.071.5.553.
Majzlan,J., & Michallik, R. The Crystal Structures, Solid Solutions and Infrared Spectra of Copiapite-Group Minerals. United States. doi:10.1180/minmag.2007.071.5.553.
Majzlan,J., and Michallik, R. Mon . "The Crystal Structures, Solid Solutions and Infrared Spectra of Copiapite-Group Minerals". United States. doi:10.1180/minmag.2007.071.5.553.
@article{osti_960035,
title = {The Crystal Structures, Solid Solutions and Infrared Spectra of Copiapite-Group Minerals},
author = {Majzlan,J. and Michallik, R.},
abstractNote = {Copiapite is a mineral of iron- and sulphate-rich acidic environments and has a general formula AFe43+(SO4)6(OH)2(H2O)20, where A = Fe2+, 2/3Fe3+, 2/3Al3+, Mg, Zn. The structure is built by infinite tetrahedral-octahedral chains and isolated octahedrally coordinated A sites. Our synthetic and natural copiapite samples can be divided into two large groups based on the orientation of the structural fragments. One group comprises copiapite phases where A = Al3+, Fe2+ or Fe3+ and we designate it as the structural type AL. The other group consists of copiapite with A = Mg2+, Zn2+ or Ni2+ and this is the structural type MG. The solid-solution series between Fe3+ and Al3+ copiapite is continuous. The series between Mg2+-Al3+, Mg2+-Fe3+ and Mg2+-Al3+-Fe3+ copiapite are not continuous; the samples with intermediate compositions contain two copiapite phases, one of the type AL and one of the type MG. The series between Mg2+ and Zn2+ copiapite is continuous only at 25 C. At 75 C, the Zn-rich portion of this system crystallizes a copiapite-like phase whose structure may be a superstructure of copiapite. The series between Al-Fe2+ and Mg-Fe2+ copiapite are not continuous and show complex behaviour of the intermediate compositions.},
doi = {10.1180/minmag.2007.071.5.553},
journal = {Mineralogical Magazine},
number = 5,
volume = 71,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}