Preliminary X-ray Fluorescence Analysis of Metallic Samples from the Chovdar Necropolis in Azerbaijan

Round 1

Reviewer 1 Report

The paper under review highlights the results of XRF analysis of a small series of non-ferrous metal objects originating from the Chovdar necropolis in Azerbaijan. The authors indicate more than two hundred burials belonging to the Late Bronze Age/Early Iron Age, dating from the end of the 2nd to the beginning of the 1st millennium BC, in which a large number of non-ferrous metal objects were found. The methodology used by the authors corresponds to the objectives of the study, and the results obtained are trustworthy. I recommend this work for publication, subject to the corrections proposed below.

Wishes and recommendations:

1. The size of the population of 18 studied subjects is minimal, so their division into 10 groups after applying the Graph Clustering procedure is a statistically insignificant distribution. With all due respect to the research approach used, the results obtained by the authors can only be considered as preliminary. Therefore, the title of the article should be corrected - for the scale of the results obtained, it is too global.

2. Line 109 - please explain why you consider sulfur only as an environmental element. In the metallurgy of this historical period, secondary sulfides and copper-iron sulfides were widely used as a source of copper among copper-containing minerals, which resulted in the presence of sulfur in the metal obtained from this raw material.

3. Lines 202-203 - correct the phrase "The historical analytical studies have shown that the amount of arsenic, tin and other metals added to copper ...". Arsenic has never been added to copper, but in some regions, including the Caucasus, copper mineralization is accompanied by arsenic mineralization. And when such minerals were used in ancient metallurgy, arsenic copper and arsenic bronze were obtained.

Author Response

1. The size of the population of 18 studied subjects is minimal, so their division into 10 groups after applying the Graph Clustering procedure is a statistically insignificant distribution. With all due respect to the research approach used, the results obtained by the authors can only be considered as preliminary. Therefore, the title of the article should be corrected - for the scale of the results obtained, it is too global.

In the manuscript we have discussed the objective difficulties which prevented a more extended study on the Chovdar samples. We nevertheless consider significant the results obtained. The finding that the ancient metallurgists used many different metallic alloys is even more interesting because it has been verified on the limited number of samples available. In any case, the result presented are, in fact, only preliminary to a more extended analysis. We thus followed the reviewer’s suggestion and changed the title of the manuscript accordingly.

2. Line 109 - please explain why you consider sulfur only as an environmental element. In the metallurgy of this historical period, secondary sulfides and copper-iron sulfides were widely used as a source of copper among copper-containing minerals, which resulted in the presence of sulfur in the metal obtained from this raw material.

The reviewer is right, sulfur should not be considered as an environmental element. We removed sulfur from the elements coming from the environment; we didn’t quantify the sulfur concentration because the element is at the limit of the detection capability of our instrument.

3. Lines 202-203 - correct the phrase "The historical analytical studies have shown that the amount of arsenic, tin and other metals added to copper ...". Arsenic has never been added to copper, but in some regions, including the Caucasus, copper mineralization is accompanied by arsenic mineralization. And when such minerals were used in ancient metallurgy, arsenic copper and arsenic bronze were obtained.

We apologize for the misleading sentence. We rephrased it as "The historical analytical studies have shown that the amount of arsenic, tin and other metals in the copper alloy...".

Reviewer 2 Report

Dear authors

I would like to thank you for your contribution to the Heritage. Overall the manuscript is written in a solid way and displays the general geochemical features of the samples. 

However,  (1) you did not mention any error margins of the techniques, or measurements, and (2) you should definitely display the raw data rather than leave it in an "on request" manner. 

I just want to highlight these two different manners and clarification of these problems will improve the quality of the manuscript. 

Author Response

(1) you did not mention any error margins of the techniques, or measurements

The determination of the errors in the sample compositions is not easy, given the absence of reference samples with the same matrix of the Chovdar bronzes. However, relative errors of the order of 10% can be estimated for the elements with concentrations higher than 1 w%. Larger relative errors (of the order of 50%) are expected for trace elements at lower concentrations. We have add these estimations to the revised manuscript.

 (2) you should display the raw data rather than leave it in an "on request" manner. 

We thank the reviewer for the suggestion. The raw XRF spectra have been provided in the supplementary material.