05 Hoiseşti L11 - white, black and red pigment Raman spectra - Romanian Database of Raman Spectroscopy
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Buzgar N., Apopei A. I., Buzatu A. (2009) - Romanian Database of Raman Spectroscopy (http://rdrs.uaic.ro)


PIGMENTS


MINERALS




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PNII - IDEI COD 2119/2008




Alexandru Ioan Cuza UniversityFaculty of Geography and Geology

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05 Hoiseşti L11

Sample image with white, black and red pigment
large image

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Raman spectrum of white pigment - Raman spectrum of Quartz
Toggle Grid Toggle Coordinates Reverse Spectrum Download Raman spectrum of white pigment .spc or .txt
Legend: white pigment______ and quartz______ Download Raman spectrum of quartz standard .spc or .txt
Raman spectrum of black pigment - Raman spectrum of Jacobsite
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Legend: black pigment______ and jacobsite______ Download Raman spectrum of jacobsite standard .txt
Raman spectrum of red pigment - Raman spectrum of Hematite
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Legend: red pigment______ and hematite______ Download Raman spectrum of hematite standard .spc or .txt
Interpretation of the white, black and red pigment Raman spectra

The Raman spectra of the white pigment are defined by background noise (BN) and strong fluorescence (F). The lack of any Raman bands, even weak ones, is due to a kaolinite clay. Constantinescu et al. (2007) have shown through XRD studies that the white pigment is a light clay (type kaolin), but the same authors mention Ca as the major chemical element in the white pigment (kaolinite clay has a low concentration of Ca, the main elements being Si and Al). Calcium carbonate is certainly absent from the white pigment, because it has a good Raman signal, at least at 1087 cm-1 (Buzgar and Apopei, 2009).

The red pigment studied contains hematite and, more frequently, quartz. The Raman spectra recorded on fine sherds from Hoiseşti and Scânteia are very similar and present the main bands of hematite. The diffuse shape of the Raman bands is caused by the fine granulation of hematite. Also, this is confirmed by high intensity peaks in the 200-300 cm-1 region and a low intensity at 1320 cm-1, which is the most intense Raman band of hematite in large crystals (Zoppi et al., 2008; Buzgar et al., 2009).

The presence of quartz is proved by the most intense band at ~465 cm-1

Quartz gives a Raman signal which is more intense than that of hematite, therefore hematite bands are less obvious in the Raman spectra.

The presence of both hematite and quartz in the red pigment excludes the use of Fe oxyhydroxides as pure red pigment. For the red color, red clay, washed several times, a process that enriched the clay with Fe oxyhydroxides (+quartz), was used. This known process is used even nowadays by pottery artisans. The source of this clay is not a special issue, as it is commonly found interbeded throughout sedimentary deposits of the Moldavian Platform.

The black pigment studied contains jacobsite. This mineral was also reported by Constantinescu et al. (2007). It is possible that it originates from the weathering crust of the Mn accumulations from Suceava county, as shown by Constantinescu et al. (2007), but we believe otherwise for two reasons. Firstly, in all samples, spectra indicated the presence of jacobsite as the only Mn mineral (absence of Mn carbonates or silicates). Secondly, several samples of black Mn corpuscles were provided by archaeologists from the “Ştefan cel Mare” University of Suceava. These Mn corpuscles were used as pigments in the Cucutenian age. Preliminary data (morphology, mineralogical composition) indicated the Nikopol manganese ore basin from Ukraine as source of these corpuscles.

References

• Jacobsite spectrum from the RRUFF project [link]

• BUZGAR N., BODI G., AŞTEFANEI D., BUZATU A. (2010) - The Raman study of white, red and black pigments used in Cucuteni Neolithic painted ceramics. Analele Stiintifice ale Universitatii “Al. I. Cuza” - Iasi, Tome 56, issue 1 [link]

• BUZGAR N., APOPEI A. I. (2009) - The Raman study on certain carbonates. Analele Stiintifice ale Universitatii “Al. I. Cuza” - Iasi, Tome 55, issue 2, 97-112 [link]

• Constantinescu, B., Bugoi, R., Pantos, E., Popovici, D., 2007. Phase and chemical composition analysis of pigments used in Cucuteni Neolithic painted ceramics. Documenta Prehistorica, XXXIV, 281-288.

• Zoppi, A., Lofrumento, C., Castellucci, E.M., Sciau, Ph., 2008. Al-for-Fe substitution in hematite: the effect of low Al concentrations in the Raman spectrum of Fe2O3. Journal of Raman Spectroscopy, 39, 40-46.