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American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian


IMPACT FACTOR 2017: 2.645

CiteScore 2017: 2.31

SCImago Journal Rank (SJR) 2017: 1.440
Source Normalized Impact per Paper (SNIP) 2017: 1.059

Online
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1945-3027
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Volume 97, Issue 10

Issues

EPR discrimination of microcrystalline calcite geomaterials

Francesco Di Benedetto
  • Corresponding author
  • Department of Chemistry, Università di Firenze, 50019 Sesto Fiorentino, Italy
  • Department of Earth Sciences, Università di Firenze, 50127 Firenze, Italy
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  • Other articles by this author:
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/ Antonella Buccianti
  • Department of Earth Sciences, Università di Firenze, 50127 Firenze, Italy
  • Istituto di Geoscienze e Georisorse (CNR-IGG), 50127 Florence, Italy
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Giordano Montegrossi / Massimo Innocenti
  • Department of Chemistry, Università di Firenze, 50019 Sesto Fiorentino, Italy
  • Istituto di Chimica dei Composti Organometallici (CNR-ICCOM), 50019 Sesto Fiorentino, Italy
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Carlo Andrea Massa / Luca A. Pardi / Maurizio Romanelli
Published Online: 2015-04-02 | DOI: https://doi.org/10.2138/am.2012.4168

Abstract

The EPR spectrum of Mn2+ in microcrystalline calcite geomaterials (e.g., marbles, travertines) possesses exceptional diagnostic characteristics, allowing to relate samples to their origin (natural/synthetic, inorganic, organogenic, …) and to evaluate the details of impurities clustering. This information, beyond their mineralogical and geochemical interest, is of paramount importance for environmental, palaeoclimatic, and cultural heritage studies.

Accessing the information hidden in the Mn2+ EPR spectrum relies on disentangling spurious self-correlation among spin Hamiltonian parameters in the powder spectrum. In the present study, this goal is achieved through a systematic comparison of the temperature dependencies of four different microcrystalline calcite geomaterials. Accordingly, an assessment of the internal correlation structure of the spin Hamiltonian parameters is provided and the most sensitive discriminating parameters, which are able to mark samples, are identified.

It has been found that the spin Hamiltonian parameters useful for discrimination purposes are those which are dependent on the ligand field interaction, whereas the Fermi contact interaction, as well as the spin-spin, spin-phonon, and spin-lattice interactions, are not able to “store” information related to formation processes, nor post-depositional events. This characteristic behavior is ascribed to the occurrence of mosaic structure and to the clustering among Mn2+ and other impurity ions, which are able to induce a strong and variable ligand field interaction.

In particular, the proposed method appears fully able to reveal the biogenic origin of microcrystalline calcites and to trace post-depositional events.

Keywords : EPR spectroscopy; microcrystalline calcite geomaterials; Mn2+; internal correlation structure; compositional data analysis; ligand field interaction; clustering of impurities

About the article

Received: 2012-03-13

Accepted: 2012-06-08

Published Online: 2015-04-02

Published in Print: 2012-10-01


Citation Information: American Mineralogist, Volume 97, Issue 10, Pages 1619–1626, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am.2012.4168.

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