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Buzgar N., Apopei A. I., Buzatu A. (2009) - Romanian Database of Raman Spectroscopy (http://rdrs.uaic.ro)


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Alexandru Ioan Cuza UniversityFaculty of Geography and Geology

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38 Hoiseşti L11

Sample image with black pigment
large image

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Raman spectrum of black pigment - Raman spectrum of Black Carbon (Isaiia) and Anatase
Toggle Grid Toggle Coordinates Reverse Spectrum Download Raman spectrum of black pigment .spc or .txt
Legend: black pigment___, Black Carbon (Isaiia)___ and anatase___ Download Raman spectrum of Black Carbon (Isaiia) standard .spc or .txt
Download Raman spectrum of Anatase standard .spc or .txt
Raman spectrum of black pigment - Raman spectrum of Black Carbon (Isaiia)
Toggle Grid Toggle Coordinates Reverse Spectrum Download Raman spectrum of black pigment .spc or .txt
Legend: black pigment___ and Black Carbon (Isaiia)___ Download Raman spectrum of Black Carbon (Isaiia) standard .spc or .txt
Interpretation of the black pigment Raman spectra

The presence of TiO2 in the white pigment on artefacts was indicated by Middleton et al. (2005). The analysis of a sample of white paint from a ceramic pot of Roman age, using FT-Raman spectroscopy, indicated that a component of the white paint was anatase.

An issue is the high frequency of appearance of rutile in relation to anatase. We believe that almost all artefacts made of fine ceramics from Hoiseşti were fired at ~900°C, which determined the transformation of anatase into rutile. Another argument which supports this theory is that the black raw ceramics from Hoiseşti present artificial white temper, made of small quantities of white kaolinite clay, where anatase and certainly not rutile is present. Moreover, in this case, the firing process was conducted below 700-750°C (above this temperature, black carbon is destroyed).

The presence of quartz and TiO2 in the kaolinite clay may suggest that the clay used as white pigment has a residual nature, formed by the weathering of igneous rocks. Clay deposits of this kind are very rare and generally occur near volcanic neogen sites (Parva and Cornăiţa - Bistriţa Năsăud region; Haita, Pietrosul and Stejar Valleys – Suceava county).

We believe that the anatase-rich kaolinite used as white pigment during the Roman age (Middleton et al., 2005) is of the same genetic type, many sources of kaolinite clay formed by weathering occuring on the territory of the Roman Empire.

For the raw black ceramic from Hoiseşti (and this sample from Scânteia), the paste used was a clay rich in organic substance. Through the firing process, the organic substance turned into black carbon. The Raman spectra of these samples clearly indicate the presence of black carbon, being similar to the spectrum of a black ceramic sample from Isaiia (Precucuteni culture).

References

• 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]

• Middleton, A.P. , Edwards, H.G.M., Middleton, P.S., Ambers, J., 2005. Identification of anatase in archaeological materials by Raman spectroscopy: implications and interpretation. Journal of Raman Spectroscopy, 36, 984-987.