A Multianalytical Approach to Identifying the White Marbles Used in Roman Imperial Sculptures from Tarraco (Hispania)

Round 1

Reviewer 1 Report

The paper “Multi-analytical approach to identify the white marbles used in 2 Roman Imperial sculptures from Tarraco (Hispania)” represents a validation of the efficacy of the set of methods (petrography, cathodoluminescence, C and O isotopies and Sr and Mn trace element composition) applied to the topic of the provenance of the ancient marbles and more precisely to the discrimination between fine and very fine marbles such as Carrara and Göktepe, often confused because of their apparent similarity.

The novelty of the paper is not into the methods used, experimented yet in previous works also cited in the paper, but in the new and correct attribution of the provenance of marbles before wrongly classified as "Carrara".

The paper is well-structured and needs only some minor revisions that are reported in the comments below.

2. Archaeological pieces

It is advisable to improve the caption of the Table 1: please clarify what MNAT, LEMLA, ICAC acronyms and and the numbers below mean. In addition, also the abbreviations num. lam. Id. Et cetera should be explained.

Finally, the references should be numbered such as the rest of the paper. So, the authors should modify the numbering in all the paper.

3. Materials and Methods

What is CL microscopy? Clarify the acronym.

4. Results and Discussion

Figure 3. Photomicrographs in crossed polarized light (on the left) and CL images (on the rigth) of 190 each sample:  Correct “right”.

Figure 4: the reference of the MGS diagram used in the paper misses.

Correct the italics and adapt the formatting of Figure 3, Figure 4, Table 2 to the other captions of the paper.

Since Göktepe is the main topic of the paper, it would be worth describing in the introduction, for example, the main differences between the 2 typologies wG1 and wG2.

Especially in sample 4, the authors could emphasize the discriminant power of the multianalytical approach used in the paper, underlining how the Afyon provenance was excluded, in spite of in some techniques (MGS, isotopes C and O) the results are partially superimposable with Göktepe and Carrara.

Eventually, have the authors considered to also include the accessory minerals to discriminate the typologies of marble?  

Author Response

Reply to Reviewer 1

Thank you very much for your review, which has helped to improve the quality of the content of the paper.

According to your suggestions:

• We have revised Table 1 , clarifying the acronyms used. However, we have maintained the format of the bibliographical references as they are the contents of the Table and not the captions of the Table, following the editorial criteria of the journal Minerals.
• We have changed the order of appearance of the acronym CL to clarify that this is the cathodoluminescence technique.
• In Figure 3: “right” is now corrected.
• In Figure 4: now the references are included.
• Formats of Figure 3, Figure 4, Table 2 are now amended.
• The main differences between wG1 and wG2 are now included (Last paragraph in Chapter 3. Materials and Methods
• We have included two sentences in the discussion of samples 1 and 4, highlighting the use of CL to rule out other options such as Afyon and Pentelicon.

Regarding the use of accessory minerals, it seems to us an important criterion in coloured marbles or in white marbles with light shades of colour, but we do not implement it in the routine identification of pure white marbles such as the ones we have studied here.

Reviewer 2 Report

Overall, the article is just great. Highly detailed on multi-method approach.

See attached for many minor corrections.

In Table 2 (and in text on pp. 9-10), use one decimal place for the C and O isotope values.

Comments for author File: Comments.pdf

Author Response

Reply to Reviewer 2

Thank you very much for your manual corrections which have helped to improve the manuscript.

Following your suggestion:

We have changed all the C and O isotopic values using one decimal.

Reviewer 3 Report

The paper “Multi-analytical approach to identify the white marbles used in Roman Imperial sculptures from Tarraco (Hispania)”, dealing with the provenance of marbles from 5 sculptures of Emperors of the Antoninii family, is well written and the data provided meaningfully discussed not only in a petrochemical perspective but also for their inferences in the archaeological and historical background of stone trading in Roman Hispania during the Middle Imperial Age.

However, some observations are reported hereafter, that I suggest the authors might check carefully.

-         In the introduction, please state that the incursion of archaeometry in provenance determination of stone materials interest not only marbles but in recent years is efficiently being applied also in the definition of the sources of other types of stones, used for the making of artifacts (Antonelli, Lazzarini 2010 doi:10.1016/j.jas.2010.02.008 ), infrastructures (Germinario et al. 2018 - 10.1002/gea.21667), or concrete additives (Dilaria et al. 2023 - https://0-doi-org.brum.beds.ac.uk/10.1038/s41598-023-30692-y ).

This is important to underline the importance of analytical methods for the reconstruction of ancient stone trading. Please consider whether to add this sentence and the suggested references

 -          Define the model of microscope used for the PLM  analysis.

 -          XRPD spectra should be reported. Please report the pattern and the phase identification.

 -          In the C and O isotopic scatterplots some possible provenances of other fine grained marbles are not reported, i.e. Hymettos or Doliana. See for example, Antonelli, Lazzarini 2015 https://0-doi-org.brum.beds.ac.uk/10.1007/s12210-015-0423-4

-          For the provenance identification, did you check the presence of plagioclases in Goktepe or Carrara Marbles?

 -          Regarding the problem of distinguishing between Goktepe, Carrara and other fine grained marbles, please consider this: Prochaska, Attanasio 2002 - https://0-doi-org.brum.beds.ac.uk/10.1016/j.jasrep.2022.103582

 -          Did you try to apply discriminant analysis for provenance identification of marbles? this techniques is being used as another screening method for provenance determination of marbles base of the multivariate treatments of trace elements of isotopes fingerprints. See in particular for Carrara marbles Prochaska 2023 - https://0-doi-org.brum.beds.ac.uk/10.1007/s00710-023-00833-2)

 -          Other minor edits: check the double spaces (i.e. at lines 15 and 57)

End of comments.

Author Response

Reply to Reviewer 3:

Thank you so much for your suggestions and comments which have served us to improve the paper

Following them:

• We have added a paragraph at the end of the introduction to frame these studies in the field of archaeometry of stone materials, highlighting the progress achieved not only for the study of marble, but also for other stone artefacts, infrastructures or concrete admixtures...in this respect we have included those three references suggested by the reviewer, readapting all the numbering of the subsequent bibliographical citations.
• In the methodology section we have changed the paragraph on the use of the microscope to indicate the model at the beginning of the paragraph and not with the explanation of the CL equipment, as it is the same microscope.
• Unlike colored marbles, in this case, XRPD diagrams have been routinely used prior to acid attack for isotopic determination, in order to verify the presence, or not, of dolomite, so their reporting in this work would not contribute anything relevant. However, we have modified the heading of the table by changing XRPD to mineralogy which is more pertinent.
• We have introduced a sentence clarifying that other fine-grained marbles, such as Doliana or Himettos, not usual in imperial portraits, have not been taken into account in the isotopic comparison, however, other fine-grained marbles very common in sculpture in Hispania have been taken into account, such as the marbles of the Estremoz Anticline.
• The presence of plagioclase in Carrara has not been detected by CL and has therefore not been mentioned. Its micrometric size would usually require its "search" by other techniques (i.e. SEM).
• We have included those two references of Prochaska as suggested by the reviewer, they are certainly two relevant papers that we should have cited. At the same time, we have added an explanatory paragraph in the Methodology section to point out the different way of approximation that we petrographers have in the sequential study of the identification of marbles...In addition we have included other three references concerning additional methods to discriminate Carrara and Göktepe.

Round 2

Reviewer 3 Report

The paper “Multi-analytical approach to identify the white marbles used in Roman Imperial sculptures from Tarraco (Hispania)”, dealing with the provenance of marbles from 5 sculptures of Emperors of the Antoninii family, is well written and the data provided meaningfully discussed not only in a petrochemical perspective but also for their inferences in the archaeological and historical background of stone trading in Roman Hispania during the Middle Imperial Age.

The paper has increased in the revised version and the suggested reviews were added and fully discussed within the text. 

My unique suggestion is to add references about the absence of Hymettos or Doliana marbles in the Western Empire, possibly by mentioning general works, reporting the distribution of white marbles in the Roman Hispania.

End of comments

Author Response

Thanks again to reviewer 3 for his/her time and interest in the subject under discussion. Unfortunately, it is impossible to document what the reviewer proposes, since there are no works where these marbles have been documented, nor is there a paper that compiles all the classical marbles that have been documented, so we would have to cite countless papers that compile which marbles have been identified, so far.