pith. sign in

arxiv: 2605.27455 · v1 · pith:UJ7EXVOAnew · submitted 2026-05-25 · ❄️ cond-mat.mtrl-sci

High-temperature instability of artificial cuprorivaite: a study using thermal analysis, X-ray powder diffractometry and polarized light microscopy

Vladimir A. Yuryev , Sergey V. Kuznetsov , Alexander A. Alexandrov , Tatyana V. Yuryeva This is my paper

Pith reviewed 2026-06-29 21:27 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords cuprorivaiteCaCuSi4O10incongruent meltingdecompositionDSCX-ray diffractiontridymiteglass
0
0 comments X

The pith

CaCuSi4O10 decomposes irreversibly by incongruent melting starting at about 1020°C.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines the high-temperature behavior of artificial cuprorivaite, CaCuSi4O10, using differential scanning calorimetry, thermogravimetry, X-ray powder diffraction, and polarized light microscopy up to 1450°C. It establishes that the compound begins to decompose through incongruent melting near 1020°C, with the DSC endothermic peak minimum at 1064.4°C. This decomposition is irreversible, as repeated heating and cooling cycles up to 1450°C do not regenerate the original phase. Instead, it forms a mixture of monoclinic tridymite crystals and a green glass of CuO-Cu2O-CaO-SiO2 composition in a roughly 12:13 weight ratio. A sympathetic reader would care because this determines the thermal limits for processing or preserving this material.

Core claim

CaCuSi4O10 powder decomposes by incongruent melting starting at about 1020°C, shown by an endothermic DSC peak with minimum at 1064.4°C. The decomposition is irreversible; cyclic annealings to 1450°C do not re-synthesize it. After two annealings to 1450°C, it transforms into acicular monoclinic tridymite crystals fused with green glass of composition CuO-Cu2O-CaO-SiO2, with tridymite to glass weight ratio about 12:13.

What carries the argument

Incongruent melting process of CaCuSi4O10 tracked via differential scanning calorimetry combined with post-annealing X-ray powder diffractometry and polarized light microscopy for phase identification.

If this is right

  • Decomposition is irreversible and subsequent cyclic annealings up to 1450°C do not cause re-synthesis of CaCuSi4O10.
  • The material transforms into acicular crystals of monoclinic tridymite fused with green glass of CuO-Cu2O-CaO-SiO2 composition.
  • The weight ratio of tridymite to glass is about 12:13 after two successive annealings to 1450°C.
  • The process begins at a temperature of about 1020°C with the DSC peak minimum at 1064.4°C.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This establishes a firm upper temperature limit beyond which cuprorivaite cannot be maintained or recovered by thermal means alone.
  • The specific glass composition produced may serve as a reference point for studying related copper silicate systems.
  • Any application involving heating above 1020°C must account for permanent conversion to the two-phase mixture.

Load-bearing premise

The observed DSC peak and post-heating XRD and microscopy patterns unambiguously identify incongruent melting and the exact product phases without contributions from sample impurities, atmosphere interactions, or instrumental artifacts.

What would settle it

Re-detection of CaCuSi4O10 in XRD patterns or microscopy after cooling from 1450°C would contradict the claim of irreversible decomposition.

Figures

Figures reproduced from arXiv: 2605.27455 by Alexander A. Alexandrov, Sergey V. Kuznetsov, Tatyana V. Yuryeva, Vladimir A. Yuryev.

Figure 1
Figure 1. Figure 1: Complementary pairs of SEM SE (a) and BSE (b) images of a sample of Egyptian blue (Kre [PITH_FULL_IMAGE:figures/full_fig_p019_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Thermal analysis curves: (a) a double-cycle experiment; (b) a single-cycle experiment; (1) tem [PITH_FULL_IMAGE:figures/full_fig_p020_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: TG (a, b) and DSC (c, d) curves of cuprorivaite powder, a [PITH_FULL_IMAGE:figures/full_fig_p021_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: TG (a) and DSC (b) curves of the cuprorivaite powder, a [PITH_FULL_IMAGE:figures/full_fig_p022_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: X-ray powder patterns (Cu Kα) of the sample (a) before the thermal analysis (original powder), (b) after the first cycle (a single-cycle experiment) and (c) after the second cycle (a double-cycle experiment). 20 [PITH_FULL_IMAGE:figures/full_fig_p022_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Complementary pairs of images of sample fragments after the single-cycle experiment, obtained [PITH_FULL_IMAGE:figures/full_fig_p023_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Complementary pairs of PM images of small pieces of the substance after the single-cycle experi [PITH_FULL_IMAGE:figures/full_fig_p024_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Effect of stage rotation: complementary pairs of PM images of the substance particles after the single-cycle experiment; the micrographs were obtained with parallel (a, c, e, g) and crossed (b, d, f, h) polars. 23 [PITH_FULL_IMAGE:figures/full_fig_p025_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Complementary pairs of PM images of sample fragments after the double-cycle experiment: par [PITH_FULL_IMAGE:figures/full_fig_p026_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Complementary pairs of polarization microscopy images of sample fragments after the double [PITH_FULL_IMAGE:figures/full_fig_p027_10.png] view at source ↗
read the original abstract

CaCuSi$_4$O$_{10}$ powder was studied by differential scanning calorimetry and thermogravimetry methods in the range from room temperature to 1450$\,^{\circ}$C at heating and cooling rates of 20$\,^{\circ}$C/min. The process of decomposition of cuprorivaite, the composition and transformations of its decomposition products during successive heat treatments were also studied by powder X-ray diffraction and polarization optical microscopy techniques. It was found that CaCuSi$_4$O$_{10}$ starts to decompose by incongruent melting at a temperature of about 1020$\,^{\circ}$C, with the minimum of the endothermic DSC peak associated with this process being at 1064.4$\,^{\circ}$C. CaCuSi$_4$O$_{10}$ decomposes irreversibly and subsequent cyclic annealings up to a temperature of 1450$\,^{\circ}$C at heating and cooling rates of 20$\,^{\circ}$C/min do not cause its re-synthesis. CaCuSi$_4$O$_{10}$ transforms into a two-phase system consisting of acicular crystals of monoclinic tridymite fused with green glass with the composition CuO$\,-\,$Cu$_2$O$\,-\,$CaO$\,-\,$SiO$_2$, with the weight ratio of tridymite to glass being about $12:13$, as a result of two successive annealings up to the temperature of 1450$\,^{\circ}$C.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The manuscript reports a multi-technique experimental study of synthetic CaCuSi4O10 (cuprorivaite) powder using DSC/TG from room temperature to 1450°C at 20°C/min heating/cooling rates, combined with post-anneal powder XRD and polarized light microscopy. The central claims are that the compound undergoes irreversible incongruent melting starting at ~1020°C (DSC endotherm minimum at 1064.4°C), transforms into monoclinic tridymite plus a CuO-Cu2O-CaO-SiO2 glass (weight ratio ~12:13 after two anneals), and shows no re-synthesis upon thermal cycling.

Significance. If the phase assignments and temperature values hold after addressing experimental controls, the work supplies new data on the high-temperature limits of cuprorivaite relevant to pigment synthesis and materials stability. The orthogonal use of thermal analysis, diffraction, and optical microscopy is a positive feature for phase identification, though the lack of quantitative uncertainties and controls limits the strength of the reported onset temperature and irreversibility conclusions.

major comments (3)
  1. [Thermal analysis] Abstract and thermal analysis description: the DSC onset of ~1020°C and peak minimum of 1064.4°C are presented as the decomposition temperature without reported calibration against standards, replicate runs, error bars, or raw curve data, which directly supports the precise numerical claim but leaves it only moderately substantiated.
  2. [Experimental methods] Experimental methods (implied by the DSC/TG description): no atmosphere (air, inert, or controlled pO2) is specified for the thermal runs. The reported glass composition involves mixed Cu valence states, so uncontrolled redox or atmosphere effects could contribute to the endotherm and undermine the assignment to incongruent melting of pure CaCuSi4O10.
  3. [Phase identification] Phase identification and results: the decomposition products and 12:13 tridymite:glass ratio are identified from post-anneal XRD and microscopy, but no pre- or post-heating chemical analysis (e.g., EDS or ICP) is described to confirm starting-material purity or exclude impurity contributions (excess SiO2 or CuO) that could produce overlapping thermal events.
minor comments (2)
  1. The abstract states the weight ratio of 12:13 but does not indicate how it was quantified (integrated XRD intensities, image analysis, or mass balance), nor are uncertainties provided.
  2. Sample synthesis and initial purity characterization of the CaCuSi4O10 powder are not detailed, which is needed to support the claim that observed signals arise solely from the target phase.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive review and the opportunity to clarify and strengthen the manuscript. We respond point-by-point to the major comments below and indicate where revisions will be made.

read point-by-point responses

  1. Referee: [Thermal analysis] Abstract and thermal analysis description: the DSC onset of ~1020°C and peak minimum of 1064.4°C are presented as the decomposition temperature without reported calibration against standards, replicate runs, error bars, or raw curve data, which directly supports the precise numerical claim but leaves it only moderately substantiated.

    Authors: We agree that the manuscript would benefit from explicit reporting of calibration and uncertainties. The DSC/TG instrument was calibrated with standard reference materials before the experiments; we will add this detail to the methods section along with the onset determination procedure (baseline-tangent intersection). An estimated uncertainty of ±5 °C will be stated based on instrument specifications and heating rate. Replicate runs were not performed due to limited synthetic sample quantity, which we will note as a limitation. Raw DSC/TG curves will be supplied as supplementary material. revision: yes

  2. Referee: [Experimental methods] Experimental methods (implied by the DSC/TG description): no atmosphere (air, inert, or controlled pO2) is specified for the thermal runs. The reported glass composition involves mixed Cu valence states, so uncontrolled redox or atmosphere effects could contribute to the endotherm and undermine the assignment to incongruent melting of pure CaCuSi4O10.

    Authors: The measurements were performed in static air, the default condition for the instrument. We will revise the experimental section to state this explicitly. The mixed Cu valence in the resulting glass is consistent with the observed decomposition products and does not alter the phase assignment supported by post-anneal XRD and microscopy; however, we acknowledge that specifying the atmosphere removes ambiguity and will do so. revision: yes

  3. Referee: [Phase identification] Phase identification and results: the decomposition products and 12:13 tridymite:glass ratio are identified from post-anneal XRD and microscopy, but no pre- or post-heating chemical analysis (e.g., EDS or ICP) is described to confirm starting-material purity or exclude impurity contributions (excess SiO2 or CuO) that could produce overlapping thermal events.

    Authors: The starting powder was confirmed as phase-pure cuprorivaite by initial XRD, and decomposition products were identified by post-anneal XRD peak matching plus polarized-light microscopy morphology. No EDS or ICP data were collected. We will add a sentence noting reliance on diffraction and optical methods without bulk chemical verification and that the 12:13 ratio is an estimate from integrated XRD intensities. This is a fair observation; the multi-technique approach still supports the reported phase assemblage. revision: partial

Circularity Check

0 steps flagged

No circularity: pure experimental measurement report with no derivations or self-referential fits

full rationale

The paper is a straightforward experimental study reporting DSC/TG curves, post-anneal XRD patterns, and optical microscopy observations on CaCuSi4O10 powder. No equations, fitted parameters, predictions derived from models, or self-citations appear in the provided text. The central claims (onset of decomposition ~1020°C, irreversibility, phase products) are presented as direct results of the measurements and standard phase identification, without any reduction to inputs by construction or load-bearing self-referential steps. This is the expected outcome for an empirical thermal analysis paper.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The work rests on standard experimental techniques and phase-identification methods with no free parameters, invented entities, or ad-hoc axioms introduced to support the central claim.

axioms (2)
  • domain assumption DSC endothermic peaks reliably indicate incongruent melting onset
    The paper directly associates the observed peak with decomposition without additional cross-validation described in the abstract.
  • domain assumption XRD and polarized-light microscopy unambiguously identify the final crystalline and glassy phases
    Phase assignment is taken as given from the standard characterization methods.

pith-pipeline@v0.9.1-grok · 5848 in / 1355 out tokens · 44513 ms · 2026-06-29T21:27:09.548716+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

73 extracted references · 59 canonical work pages

  1. [1]

    CaCuSi 4O10, in: J

    Cuprorivaite. CaCuSi 4O10, in: J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols (Eds.), Handbook of Mineralogy, V ol. II, Mineralogical Society of Amer- ica, Chantilly, V A, USA, 2003. URL http://www.handbookofmineralogy.org/pdfs/cuprorivaite.pdf

    2003

  2. [2]

    URL https://www.mindat.org/min-1189.html

    Cuprorivaite, Hudson Institute of Mineralogy, Keswick, V A, USA, dba Min- dat.org (2019). URL https://www.mindat.org/min-1189.html

    2019

  3. [3]

    Fabbrizzi, Painting conditioned by chemistry: the case of Egyptian and ultramarine blue pigments, ChemTexts 11 (9) (2025) 1–20.doi:10.1007/ BF00376668

    L. Fabbrizzi, Painting conditioned by chemistry: the case of Egyptian and ultramarine blue pigments, ChemTexts 11 (9) (2025) 1–20.doi:10.1007/ BF00376668. URL https://doi.org/10.1007/s40828-025-00204-8

    work page doi:10.1007/s40828-025-00204-8 2025

  4. [4]

    Riederer, Egyptian blue, in: E

    J. Riederer, Egyptian blue, in: E. W. FitzHugh (Ed.), Artists' Pigments: A Handbook of their History and Characteristics, V ol. 3, National Gallery of Art, Washington, USA, 2012, pp. 23–45. URL https://www.nga.gov/content/dam/ngaweb/research/publications/pdfs/ artists-pigments-vol3.pdf

    2012

  5. [5]

    A. P. Laurie, The Materials of the Painter’s Craft in Europe and Egypt: from Earliest Times to the End of the XVIIth Century, with Some Account of Their Preparation and Use, T. N. Foulis, London & Edinburgh, UK, 1910. URL https://archive.org/details/cu31924016809927/page/n12/mode/2up

    1910

  6. [6]

    Jaksch, W

    H. Jaksch, W. Seipel, K. L. Weiner, A. E. Goresy, Egyptian blue – Cuprorivaite a window to ancient Egyptian technology, Naturwiss. 70 (11) (1983) 525–535. doi:10.1007/BF00376668. URL https://doi.org/10.1007/BF00376668

    work page doi:10.1007/bf00376668 1983

  7. [7]

    G. D. Hatton, A. J. Shortland, M. S. Tite, The production technology of Egyptian blue and green frits from second millennium BC Egypt and Mesopotamia, J. Ar- 28 chaeol. Sci. 35 (6) (2008) 1591–1604.doi:10.1016/j.jas.2007.11.008. URL https://doi.org/10.1016/j.jas.2007.11.008

    work page doi:10.1016/j.jas.2007.11.008 2008

  8. [8]

    Aloiz, J

    E. Aloiz, J. G. Douglas, A. Nagel, Painted plaster and glazed brick fragments from Achaemenid Pasargadae and Persepolis, Iran, Heritage Science 4 (1) (2016) 3.doi:10.1186/s40494-016-0072-7. URL https://doi.org/10.1186/s40494-016-0072-7

    work page doi:10.1186/s40494-016-0072-7 2016

  9. [9]

    Easthaugh, V

    N. Easthaugh, V . Walsh, T. Chaplin, R. Siddall, Pigment Compendium: A Dic- tionary of Historical Pigments, Routledge, London, UK, 2004.doi:10.4324/ 9780080473765. URL https://doi.org/10.4324/9780080473765

    work page doi:10.4324/9780080473765 2004

  10. [10]

    Couleurs Fines et Matériel pour la Peinture a l’Huile, Lefranc, Paris, France, 1930, Ch

    Fabrique de Couleurs & Vernis. Couleurs Fines et Matériel pour la Peinture a l’Huile, Lefranc, Paris, France, 1930, Ch. Couleurs extra-fines en tubes, p. 10

    1930

  11. [11]

    Birch. Spring

    S. A. Pisareva, I. N. Shibanova, I. F. Kadikova, E. A. Morozova, T. V . Yuryeva, I. B. Afanasyev, V . A. Yuryev, Identification of CaCuSi4O10 (Egyptian blue) in the “Birch. Spring” painting by Robert Falk (1907) using photoluminescence, J. Cult. Herit. (2021).doi:10.1016/j.culher.2021.05.005. URL https://doi.org/10.1016/j.culher.2021.05.005

    work page doi:10.1016/j.culher.2021.05.005 1907

  12. [12]

    Berke, The invention of blue and purple pigments in ancient times, Chem

    H. Berke, The invention of blue and purple pigments in ancient times, Chem. Soc. Rev. 36 (2007) 15–30.doi:10.1039/B606268G. URL http://doi.org/10.1039/B606268G

    work page doi:10.1039/b606268g 2007

  13. [13]

    Panagiotaki, M

    M. Panagiotaki, M. S. Tite, Y . Maniatis, Egyptian Blue in Egypt and beyond: the Aegean and the Near East, in: P. Kousoulis, N. Lazaridis (Eds.), Proceedings of the Tenth International Congress of Egyptologists, University of the Aegean, Rhodes 22–29 May 2008, V ol. II of Orientalia Lovaniensia Analecta 241, Peeters, Leuven – Paris – Bristol, CT, 2015, pp...

    2008

  14. [14]

    A. K. Marketou, The pigment production site of the ancient agora of Kos (Greece): Revisiting the material evidence, Thiasos 8.1 (2019) 61–80. 29 URL http://www.thiasos.eu/wp-content/uploads/2019/06/02-2019-Marketou_ 20190610.pdf

    2019

  15. [15]

    Y . I. Grenberg, S. A. Pisareva, A. B. Levstein, The study of the paint layer compo- sition in the samples of mural paintings of Erebuni, Preliminary report on research project (topic 7.3), The All-Union Scientific-Research Institute for Restoration, Moscow, USSR, in Russian (1982).doi:10.13140/RG.2.2.25685.17129. URL https://doi.org/10.13140/RG.2.2.25685.17129

    work page doi:10.13140/rg.2.2.25685.17129 1982

  16. [16]

    S. A. Pisareva, V . N. Kireeva, The study of the paint layer composition in the samples of mural paintings of Erebuni, in: Y . I. Grenberg (Ed.), Investigations of monumental painting of Armenia and Novgorod, no. 6 in Culture and Arts in the USSR. Series: Restoration of Historical and Cultural Monuments. Express Information, The Lenin State Library of the...

    work page arXiv 1987

  17. [17]

    Dardeniz, E

    G. Dardeniz, E. Akalßn, Coloring Urartu: A local variety of Egyptian blue in Anatolia, Paléorient 51 (2025) 89–98.doi:10.4000/15apg. URL https://doi.org/10.4000/15apg

    work page doi:10.4000/15apg 2025

  18. [18]

    G. M. Ingo, A. Çilingiro ˘glu, G. D. Carlo, A. Batmaz, T. D. Caro, C. Riccucci, E. I. Parisi, F. Faraldi, Egyptian Blue cakes from the Ayanis fortress (Eastern Anatolia, Turkey): micro-chemical and -structural investigations for the identification of manufacturing process and provenance, J. Archaeol. Sci. 40 (12) (2013) 4283– 4290.doi:10.1016/j.jas.2013.0...

    work page doi:10.1016/j.jas.2013.06.016 2013

  19. [19]

    Ormanci, Non-destructive characterization of Egyptian Blue cakes and wall painting fragments from the east of Lake Van, Turkey, Spectrochim

    Ö. Ormanci, Non-destructive characterization of Egyptian Blue cakes and wall painting fragments from the east of Lake Van, Turkey, Spectrochim. Acta A 229 30 (2020) 117889.doi:10.1016/j.saa.2019.117889. URL https://doi.org/10.1016/j.saa.2019.117889

    work page doi:10.1016/j.saa.2019.117889 2020

  20. [20]

    R. Linn, E. H. Cline, A. Yasur-Landau, The advantages of visible induced lumi- nescence technique for the investigation of Aegean-style wall painting. A case study from Tel Kabri, Israel, in: J. Becker, J. Jungfleisch, C. von Rüden (Eds.), Tracing Technoscapes. The Production of Bronze Age Wall Paintings in the East- ern Mediterranean, Sidestone Press, Le...

    2018

  21. [21]

    Ganio, J

    M. Ganio, J. Salvant, J. Williams, L. Lee, O. Cossairt, M. Walton, Investi- gating the use of Egyptian blue in Roman Egyptian portraits and panels from Tebtunis, Egypt, Appl. Phys. A 121 (3) (2015) 813–821.doi:10.1007/ s00339-015-9424-5. URL https://doi.org/10.1007/s00339-015-9424-5

    work page doi:10.1007/s00339-015-9424-5 2015

  22. [22]

    Salvant, J

    J. Salvant, J. Williams, M. Ganio, F. Casadio, C. Daher, K. Sutherland, L. Mon- ico, F. Vanmeert, S. De Meyer, K. Janssens, C. Cartwright, M. Walton, A Roman Egyptian painting workshop: Technical investigation of the portraits from Tebtu- nis, Egypt, Archaeometry 60 (4) (2018) 815–833.doi:10.1111/arcm.12351. URL https://doi.org/10.1111/arcm.12351

    work page doi:10.1111/arcm.12351 2018

  23. [23]

    Horsemen

    G. E. Veresotskaya, Restoration of a fragment of the “Horsemen” archae- ological painting from Old Nisa, in: Artistic Heritage. Conservation, Re- search, Restoration, no. 23(53), The State Research Institute for Restoration, Moscow, Russia, 2006, pp. 166–174, 190, 191, Also in: ARTconservation, https://web.archive.org/web/20121111061508/http://art-con.ru/...

    work page arXiv 2006

  24. [24]

    A. M. Rosenqvist, Analyser an skerd og skjold fra Bø-funnet (Analysis of sword and shield from the Bø-find), Viking 23 (1959) 29–34. URL https://www.duo.uio.no/bitstream/handle/10852/37585/1959-vol-23.pdf

    1959

  25. [25]

    M. G. Canti, J. L. Heathcote, Microscopic Egyptian blue (synthetic cuprorivaite) from sediments at two archaeological sites in West Central England, J. Archaeol. 31 Sci. 29 (8) (2002) 831–836.doi:10.1006/jasc.2001.0717. URL http://doi.org/10.1006/jasc.2001.0717

    work page doi:10.1006/jasc.2001.0717 2002

  26. [26]

    Nicola, L

    M. Nicola, L. M. Seymour, M. Aceto, E. Priola, R. Gobetto, A. Masic, Late production of Egyptian blue: synthesis from brass and its character- istics, Archaeol. Anthrop. Sci. 11 (10) (2019) 5377–5392.doi:10.1007/ s12520-019-00873-w. URL https://doi.org/10.1007/s12520-019-00873-w

    work page doi:10.1007/s12520-019-00873-w 2019

  27. [27]

    Review of energy-efficient train control and timetabling

    M. Nicola, M. Aceto, V . Gheroldi, R. Gobetto, G. Chiari, Egyptian blue in the Castelseprio mural painting cycle. Imaging and evidence of a non-traditional manufacture, J. Archaeol. Sci. Rep. 19 (2018) 465–475.doi:10.1016/j. jasrep.2018.03.031. URL https://doi.org/10.1016/j.jasrep.2018.03.031

    work page doi:10.1016/j 2018

  28. [28]

    Lluveras, A

    A. Lluveras, A. Torrents, P. Girález, M. Vendrell-Saz, Evidence for the use of Egyptian blue in an 11th century mural altarpiece by SEM–EDS, FTIR and SR XRD (church of Sant Pere, Terrassa, Spain), Archaeometry 52 (2) (2010) 308–319.doi:10.1111/j.1475-4754.2009.00481.x. URL https://doi.org//10.1111/j.1475-4754.2009.00481.x

    work page doi:10.1111/j.1475-4754.2009.00481.x 2010

  29. [29]

    Bredal-Jørgensen, J

    J. Bredal-Jørgensen, J. Sanyova, V . Rask, M. L. Sargent, R. H. Therkildsen, Striking presence of Egyptian blue identified in a painting by Giovanni Bat- tista Benvenuto from 1524, Anal. Bioanal. Chem. 401 (4) (2011) 1433–1439. doi:10.1007/s00216-011-5140-y. URL https://doi.org/10.1007/s00216-011-5140-y

    work page doi:10.1007/s00216-011-5140-y 2011

  30. [30]

    Sgamellotti, C

    A. Sgamellotti, C. Anselmi, An evergreen blue. Spectroscopic properties of Egyp- tian blue from pyramids to Raphael, and beyond, Inorganica Chim. Acta 530 (2022) 120699.doi:10.1016/j.ica.2021.120699. URL https://doi.org/10.1016/j.ica.2021.120699

    work page doi:10.1016/j.ica.2021.120699 2022

  31. [31]

    S. M. Borisov, C. Würth, U. Resch-Genger, I. Klimant, New life of ancient pig- ments: Application in high-performance optical sensing materials, Anal. Chem. 32 85 (19) (2013) 9371–9377.doi:10.1021/ac402275g. URL https://doi.org/10.1021/ac402275g

    work page doi:10.1021/ac402275g 2013

  32. [32]

    Selvaggio, S

    G. Selvaggio, S. Kruss, Preparation, properties and applications of near-infrared fluorescent silicate nanosheets, Nanoscale 14 (2022) 9553–9575.doi:10.1039/ D2NR02967G. URL https://doi.org/10.1039/D2NR02967G

    work page doi:10.1039/d2nr02967g 2022

  33. [33]

    Sobik, O

    P. Sobik, O. Jeremiasz, P. Nowak, A. Sala, B. Pawłowski, G. Kulesza-Matlak, A. Sypie´n, K. Drabczyk, Towards efficient luminescent solar energy concentrator using cuprorivaite infrared phosphor (CaCuSi4O10)—effect of dispersing method on photoluminescence intensity, Materials 14 (14) (2021) 3952.doi:10.3390/ ma14143952. URL https://doi.org/10.3390/ma14143952

    work page doi:10.3390/ma14143952 2021

  34. [34]

    J. L. Tyler, R. L. Sacci, J. Ning, D. R. Mullins, K. Liang, J. Nanda, J. Sun, M. Naguib, Egyptian blue: from pigment to battery electrodes, RSC Adv. 11 (32) (2021) 19885–19889.doi:10.1039/D1RA00956G. URL http://dx.doi.org/10.1039/D1RA00956G

    work page doi:10.1039/d1ra00956g 2021

  35. [35]

    Selvaggio, A

    G. Selvaggio, A. Chizhik, R. Nißler, l. Kuhlemann, D. Meyer, L. Vuong, H. Preiß, N. Herrmann, F. A. Mann, Z. Lv, T. A. Oswald, A. Spreinat, L. Erpenbeck, J. Großhans, V . Karius, A. Janshoff, J. Pablo Giraldo, S. Kruss, Exfoliated near infrared fluorescent silicate nanosheets for (bio)photonics, Nat. Commun. 11 (1) (2020) 1495.doi:10.1038/s41467-020-15299...

    work page doi:10.1038/s41467-020-15299-5 2020

  36. [36]

    Selvaggio, N

    G. Selvaggio, N. Herrmann, B. Hill, R. Dervi¸ so˘glu, S. Jung, M. Weitzel, M. Di- narvand, D. Stalke, L. Andreas, S. Kruss, Covalently functionalized Egyptian blue nanosheets for near-infrared bioimaging, ACS Appl. Bio Mater. (2022). doi:10.1021/acsabm.2c00872. URL https://doi.org/10.1021/acsabm.2c00872

    work page doi:10.1021/acsabm.2c00872 2022

  37. [37]

    C. He, C. Dong, L. Yu, Y . Chen, Y . Hao, Ultrathin 2D inorganic ancient pigment decorated 3D-printing scaffold enables photonic hyperthermia of osteosarcoma in 33 NIR-II biowindow and concurrently augments bone regeneration, Adv. Sci. 8 (19) (2021) 2101739.doi:10.1002/advs.202101739. URL https://doi.org/10.1002/advs.202101739

    work page doi:10.1002/advs.202101739 2021

  38. [38]

    Errington, G

    B. Errington, G. Lawson, S. W. Lewis, G. D. Smith, Micronised egyptian blue pigment: A novel near-infrared luminescent fingerprint dusting powder, Dyes Pigm. 132 (2016) 310–315.doi:10.1016/j.dyepig.2016.05.008. URL https://doi.org/10.1016/j.dyepig.2016.05.008

    work page doi:10.1016/j.dyepig.2016.05.008 2016

  39. [39]

    Shahbazi, J

    S. Shahbazi, J. V . Goodpaster, G. D. Smith, T. Becker, S. W. Lewis, Studies into exfoliation and coating of egyptian blue in methanol for application to the detection of latent fingermarks, Sci. Justice 62 (4) (2022) 455–460.doi:10. 1016/j.scijus.2022.05.004. URL https://doi.org/10.1016/j.scijus.2022.05.004

    work page doi:10.1016/j.scijus.2022.05.004 2022

  40. [40]

    Shahbazi, J

    S. Shahbazi, J. V . Goodpaster, G. D. Smith, T. Becker, S. W. Lewis, Prepara- tion, characterization, and application of a lipophilic coated exfoliated Egyptian blue for near-infrared luminescent latent fingermark detection, Forensic Chem. 18 (2020) 100208.doi:10.1016/j.forc.2019.100208. URL https://doi.org/10.1016/j.forc.2019.100208

    work page doi:10.1016/j.forc.2019.100208 2020

  41. [41]

    Y . Chen, M. Kan, Q. Sun, P. Jena, Structure and properties of egyptian blue mono- layer family: XCuSi4O10 (X=Ca, Sr, and Ba), J. Phys. Chem. Lett. 7 (3) (2016) 399–405.doi:10.1021/acs.jpclett.5b02770. URL https://doi.org/10.1021/acs.jpclett.5b02770

    work page doi:10.1021/acs.jpclett.5b02770 2016

  42. [42]

    Johnson-McDaniel, C

    D. Johnson-McDaniel, C. A. Barrett, A. Sharafi, T. T. Salguero, Nanoscience of an ancient pigment, J. Am. Chem. Soc. 135 (2013) 1677–1679.doi:10.1021/ ja310587c. URL https://doi.org/10.1021/ja310587c

    work page doi:10.1021/ja310587c 2013

  43. [43]

    Pozza, D

    G. Pozza, D. Ajò, G. Chiari, F. D. Zuane, M. Favaro, Photoluminescence of the inorganic pigments Egyptian blue, Han blue and Han purple, J. Cult. Herit. 1 (4) (2000) 393–398.doi:10.1016/S1296-2074(00)01095-5. URL https://doi.org/10.1016/S1296-2074(00)01095-5 34

    work page doi:10.1016/s1296-2074(00)01095-5 2000

  44. [44]

    Accorsi, G

    G. Accorsi, G. Verri, M. Bolognesi, N. Armaroli, C. Clementi, C. Miliani, A. Romani, The exceptional near-infrared luminescence properties of cuprori- vaite (Egyptian blue), Chem. Commun. 23 (2009) 3392–3394.doi:10.1039/ B902563D. URL https://doi.org/10.1039/B902563D

    work page doi:10.1039/b902563d 2009

  45. [45]

    Berdahl, S

    P. Berdahl, S. K. Boocock, G. C.-Y . Chan, S. S. Chen, R. M. Levinson, M. A. Zalich, High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M=Ca, Sr, Ba), J. Appl. Phys. 123 (19) (2018) 193103.doi: 10.1063/1.5019808. URL https://doi.org/10.1063/1.5019808

    work page doi:10.1063/1.5019808 2018

  46. [46]

    Y .-J. Li, S. Ye, C.-H. Wang, X.-M. Wang, Q.-Y . Zhang, Temperature-dependent near-infrared emission of highly concentrated Cu 2+ in CaCuSi4O10 phosphor, J. Mater. Chem. C 2 (48) (2014) 10395–10402.doi:10.1039/C4TC01966K. URL http://dx.doi.org/10.1039/C4TC01966K

    work page doi:10.1039/c4tc01966k 2014

  47. [47]

    Binet, J

    L. Binet, J. Lizion, S. Bertaina, D. Gourier, Magnetic and new optical properties in the UV−visible range of the Egyptian blue pigment cuprorivaite CaCuSi 4O10, J. Phys. Chem. C 125 (45) (2021) 25189–25196.doi:10.1021/acs.jpcc. 1c06060. URL https://doi.org/10.1021/acs.jpcc.1c06060

    work page doi:10.1021/acs.jpcc 2021

  48. [48]

    V . A. Yuryev, T. V . Yuryeva, I. F. Kadikova, S. A. Malykhin, A. A. Klimenko, K. V . Chizh, Photoluminescence and cathodoluminescence of CaCu(Si 2O5)2, Opt. Mater. 140 (2023) 113892.doi:10.1016/j.optmat.2023.113892. URL https://doi.org/10.1016/j.optmat.2023.113892

    work page doi:10.1016/j.optmat.2023.113892 2023

  49. [49]

    S. A. Kozyukhin, S. I. Bezzubov, A. V . Gavrikov, A. V . Semeno, A. N. Samarin, V . V . Glushkov, High-frequency electron spin resonance study of a single crystal of Egyptian blue at 4.2 k, Mendeleev Commun. 36 (2026) 1–3.doi:10.71267/ mencom.7907. URL https://doi.org/10.71267/mencom.7907 35

    work page doi:10.71267/mencom.7907 2026

  50. [50]

    Jenkins, R

    R. Jenkins, R. L. Snyder, Introduction to X-ray Powder Diffractometry, Wiley, New York, 1996.doi:10.1002/9781118520994. URL https://doi.org/10.1002/9781118520994

    work page doi:10.1002/9781118520994 1996

  51. [51]

    Gražulis, D

    S. Gražulis, D. Chateigner, R. T. Downs, A. T. Yokochi, M. Quirós, L. Lutterotti, E. Manakova, J. Butkus, P. Moeck, A. Le Bail, Crystallography Open Database – an open-access collection of crystal structures, J. Appl. Crystallogr. 42 (2009) 726–729.doi:10.1107/S0021889809016690. URL https://doi.org/10.1107/S0021889809016690

    work page doi:10.1107/s0021889809016690 2009

  52. [52]

    R. L. Feller, M. Bayard, Terminology and procedures used in the systematic examination of pigment particles with the polarizing microscope, in: R. L. Feller (Ed.), Artists' Pigments: A Handbook of their History and Characteristics, V ol. 1, National Gallery of Art, Washington, USA, 1986, pp. 285–298. URL https://www.nga.gov/content/dam/ngaweb/research/pub...

    1986

  53. [53]

    Inoué, Polarization microscopy, Curr

    S. Inoué, Polarization microscopy, Curr. Protoc. Cell Biol. 13 (1) (2002) 4.9.1– 4.9.27.doi:10.1002/0471143030.cb0409s13. URL https://doi.org/10.1002/0471143030.cb0409s13

    work page doi:10.1002/0471143030.cb0409s13 2002

  54. [54]

    Eastaugh, V

    N. Eastaugh, V . Walsh, Part 2 – Optical Microscopy of Historical Pigments, in: The Pigment Compendium: A Dictionary and Optical Microscopy of Historical Pigments, Routledge, NY , USA, 2008, p. 507.doi:10.4324/9780080454573. URL https://doi.org/10.4324/9780080454573

    work page doi:10.4324/9780080454573 2008

  55. [55]

    Eastaugh, V

    N. Eastaugh, V . Walsh, Optical microscopy, in: J. H. Stoner, R. Rushfield (Eds.), Conservation of Easel Paintings, Routledge, London, 2020, Ch. 18.doi:10. 4324/9780429399916. URL https://doi.org/10.4324/9780429399916

    work page doi:10.4324/9780429399916 2020

  56. [56]

    Bensch, M

    W. Bensch, M. Schur, Crystal structure of calcium copper phyllo- decaoxotetrasilicate, CaCuSi 4O10, Z. Kristallogr. Cryst. Mater. 210 (7) (1995) 530–530.doi:10.1524/zkri.1995.210.7.530. URL https://doi.org/10.1524/zkri.1995.210.7.530 36

    work page doi:10.1524/zkri.1995.210.7.530 1995

  57. [57]

    H. Yang, C. T. Prewitt, Crystal structure and compressibility of a two-layer polytype of pseudowollastonite (CaSiO3), Am. Mineral. 84 (1999) 1902–1905. doi:10.2138/am-1999-11-1217. URL https://doi.org/10.2138/am-1999-11-1217

    work page doi:10.2138/am-1999-11-1217 1999

  58. [58]

    J. I. Langford, D. Louër, High-resolution powder diffraction studies of cop- per(II) oxide, J. Appl. Crystallogr. 24 (2) (1991) 149–155.doi:10.1107/ S0021889890012092. URL https://doi.org/10.1107/S0021889890012092

    work page doi:10.1107/s0021889890012092 1991

  59. [59]

    Sato, X-ray study of tridymite, Mineral

    M. Sato, X-ray study of tridymite, Mineral. J. 4 (2) (1963) 115–130.doi:10. 2465/minerj1953.4.115. URL https://doi.org/10.2465/minerj1953.4.115

    work page doi:10.2465/minerj1953.4.115 1963

  60. [60]

    Kihara, Thermal change in unit-cell dimensions, and a hexagonal structure of tridymite, Z

    K. Kihara, Thermal change in unit-cell dimensions, and a hexagonal structure of tridymite, Z. Kristallogr. Cryst. Mater. 148 (3–4) (1978) 237–254.doi:doi: 10.1524/zkri-1978-3-406. URL https://doi.org/10.1524/zkri-1978-3-406

    work page doi:10.1524/zkri-1978-3-406 1978

  61. [61]

    Niggli, XII

    P. Niggli, XII. Die Kristallstruktur einiger Oxyde I, Z. Kristallogr. Cryst. Mater. 57 (1–6) (1922) 253–299.doi:doi:10.1524/zkri.1922.57.1.253. URL https://doi.org/10.1524/zkri.1922.57.1.253

    work page doi:10.1524/zkri.1922.57.1.253 1922

  62. [62]

    Fiquet, P

    G. Fiquet, P. Richet, G. Montagnac, High-temperature thermal expansion of lime, periclase, corundum and spinel, Phys. Chem. Min. 27 (1999) 103–111.doi:doi: 10.1007/s002690050246. URL https://doi.org/10.1007/s002690050246

    work page doi:10.1007/s002690050246 1999

  63. [63]

    Dollase, W

    W. Dollase, W. Baur, The superstructure of meteoritic low tridymite solved by computer simulation, Am. Mineral. 61 (9–10) (1976) 971–978. URL https://msaweb.org/AmMin/AM61/AM61_971.pdf

    1976

  64. [64]

    M. S. Tite, M. Bimson, M. R. Cowell, The technology of Egyptian Blue, in: M. Bimson, I. C. Freestone (Eds.), Early Vitreous Materials, British Museum Occasional Paper, No. 56, British Museum, London, UK, 1987, pp. 39–46. 37

    1987

  65. [65]

    K. A. Shahid, F. P. Glasser, Thermal properties of tridymite: 25°C–300°C, J. Therm. Anal. Calorim. 2 (2) (1970) 181–190.doi:10.1007/BF01911349. URL https://doi.org/10.1007/BF01911349

    work page doi:10.1007/bf01911349 1970

  66. [66]

    H. A. Graetsch, O. W. Flörke, X-ray powder diffraction patterns and phase rela- tionship of tridymite modifications, Z. Kristallogr. Cryst. Mater. 195 (1–4) (1991) 31–48.doi:10.1524/zkri.1991.195.14.31. URL https://doi.org/10.1524/zkri.1991.195.14.31

    work page doi:10.1524/zkri.1991.195.14.31 1991

  67. [67]

    P. J. Heaney, Structure and chemistry of the low-pressure silica polymorphs, in: P. J. Heaney, C. T. Prewitt, G. V . Gibbs (Eds.), Silica: Physical Behav- ior, Geochemistry, and Materials Applications, V ol. 29 of Reviews in Miner- alogy, De Gruyter, Berlin, Boston, 1994, Ch. 1, pp. 1–40.doi:10.1515/ 9781501509698-006. URL https://doi.org/10.1515/97815015...

    work page doi:10.1515/9781501509698-006 1994

  68. [68]

    Hirose, K

    T. Hirose, K. Kihara, M. Okuno, S. Fujinami, K. Shinoda, X-ray, DTA and Ra- man studies of monoclinic tridymite and its higher temperature orthorhombic modification with varying temperature, J. Miner. Petrol. Sci. 100 (2005) 55–69. doi:10.2465/JMPS.100.55. URL https://doi.org/10.2465/JMPS.100.55

    work page doi:10.2465/jmps.100.55 2005

  69. [69]

    Huang, P

    W.-L. Huang, P. J. Wyllie, Melting and subsolidus phase relationships for CaSiO3 to 35 kilobars pressure, Am. Mineral. 60 (3–4) (1975) 213–217. URL https://pubs.geoscienceworld.org/msa/ammin/article-abstract/60/3-4/ 213/542957/Melting-and-subsolidus-phase-relationships-for?redirectedFrom= fulltext

    1975

  70. [70]

    Y . V . Seryotkin, E. V . Sokol, S. N. Kokh, Natural pseudowollastonite: Crystal structure, associated minerals, and geological context, Lithos 134–135 (2012) 75–90.doi:10.1016/j.lithos.2011.12.010. URL https://doi.org/10.1016/j.lithos.2011.12.010

    work page doi:10.1016/j.lithos.2011.12.010 2012

  71. [71]

    S. H. Abd El Rahim, A. A. Melegy, E. M. A. Hamzawy, Wollastonite- pseudowollastonite from silica fume, limestone and glass cullet composite, In- 38 terceram. 66 (6) (2017) 232–236.doi:10.1007/BF03401217. URL https://doi.org/10.1007/BF03401217

    work page doi:10.1007/bf03401217 2017

  72. [72]

    Pushcharovsky, L

    D. Pushcharovsky, L. Bindi, Secrets from the Depths of Space and Earth: un- raveling newly discovered high-pressure polymorphs in meteorites and diamond inclusions, Minerals 15 (2) (2025) 144.doi:10.3390/min15020144. URL https://10.3390/min15020144

    work page doi:10.3390/min15020144 2025

  73. [73]

    URL https://www.mindat.org/min-4015.html 39

    Tridymite, Hudson Institute of Mineralogy, Keswick, V A, USA, dba Mindat.org. URL https://www.mindat.org/min-4015.html 39