Origin of Critical Metals in Fe–Ni Laterites from the Balkan Peninsula: Opportunities and Environmental Risk
, Magdalena Laskou 1, Demetrios G. Eliopoulos 2,†, Ifigeneia Megremi 1, Sofia Kalatha 1 and George D. Eliopoulos 3Round 1
Reviewer 1 Report
The paper proposed by the authors constitutes a review, supplemented by new data, on the mineralizations to critical metals associated with the lateritic and bauxitic Fe-Ni deposits of the Balkan region. Furthermore, on the basis of literature data supplemented by new data, considerations are also made on the environmental risks associated with a possible exploitation of the deposits.
I found the paper very interesting and based on a solid dataset, fully within the topics of Minerals. However, I have some points to highlight and some suggestions to provide:
1) the parts on mineral deposits and the part of the environmental study still appear to be poorly integrated, in my opinion the authors should revise the text in different points (e.g., in the introduction) to try to harmonize them;
2) The Methods chapter is not complete: all the analytical methods and procedures utinized for the environmental study are missing, and must be integrated;
3) In my opinion, a figure with schematic stratigraphic sections of the main deposits, inserted in the geology chapter would greatly help the reader (and improve the work);
4) English is generally good, but requires a general revision, given the number of typos and small errors (I have reported many of them in the attached file); moreover, several sentences are too long, and could easily be broken down into two or three parts.
Other minor remarks and suggestions are present in the attached file.
Comments for author File: 
Comments.pdf
Author Response
Reply to Reviewer 1
Comments and Suggestions for Authors
The paper proposed by the authors constitutes a review, supplemented by new data, on the mineralizations to critical metals associated with the lateritic and bauxitic Fe-Ni deposits of the Balkan region. Furthermore, on the basis of literature data supplemented by new data, considerations are also made on the environmental risks associated with a possible exploitation of the deposits. I found the paper very interesting and based on a solid dataset, fully within the topics of Minerals.
Dear Reviewer,
Thank you very much for your constructive comments, suggestions and linguistic improvement of the text.
However, I have some points to highlight and some suggestions to provide:
1) the parts on mineral deposits and the part of the environmental study still appear to be poorly integrated, in my opinion the authors should revise the text in different points (e.g., in the introduction) to try to harmonize them;
Reply: Concerning the part of the environmental risk, this section re-organized, and text in the sections of the Introduction and Discussion was added.
2) The Methods chapter is not complete: all the analytical methods and procedures utinized for the environmental study are missing, and must be integrated.
Reply: Although the analytical methods applied for the determination of major and trace elements in the rocks, laterite ores, and groundwater and water leachates composition, including chromium stable isotopes are provided in the relative publications, a brief outline is given here.
3) In my opinion, a figure with schematic stratigraphic sections of the main deposits, inserted in the geology chapter would greatly help the reader (and improve the work);
Reply: Such a figure was missing indeed. Figure 2A was added.
4) English is generally good, but requires a general revision, given the number of typos and small errors (I have reported many of them in the attached file); moreover, several sentences are too long, and could easily be broken down into two or three parts.
Other minor remarks and suggestions are present in the attached file.
Reply: Thank you. They were improved.
Comments on the edited pdf copy of the manuscript
Line 30: Integrate also here the environmental study.
Reply: It was done.
Line 33: In this part of the text, also the environmental part of your study must be introduced
Reply: A relative paragraph was added.
Line 52: something seems missing here, perhaps "made by", or "implemented by"?
Reply: It was completed.
Line 54: a verb (e.g., "are recognized"?) seems missing...
Reply: It was completed.
Line 55: for the Fe oxide type, I presume
Reply: It was corrected.
Line 73: You must integrate analytical methods and procedures utilized in the environmental study, e.g, 1) the samples from metallurgical slags 2) samples and description of analytical procedures for leaching tests 3) synchrotron - based techniques, etc.
Reply: A brief outline is given here now.
Line 94: This chapter would greatly benefit from a figure with schematic stratigraphic sections of the most representative deposits.
Reply: Figure 2A with schematic stratigraphic sections of the most representative deposits is given.
Line 118: This small sentence seems to me out of the context, it's probably better to put it before or after in the text
Reply: It was removed before.
Line 126: orthopyroxene OR opx, not both
Reply: It was corrected.
Line 149: mineralogy
Reply: corrected
Line 206: IMHO, you should move this sentence after the next one
Reply: It was done.
Line 231: concentric?
Reply: corrected.
Line 235: this sentence is rather cryptic, please rewrite!
Reply: It was re-written.
Line 250: (CoO+NiO) versus MgO
Reply: Corrected.
Line 275: evidenced
Reply: Corrected.
Table 3: something is wrong with this rows...
Reply: All Tables are in the form of picture now.
Line 328, figure 11: please in this figure display correlation trends as LINES
Reply: Sorry, this is the line type, but due to the logarithmic scale it is not LINE.
Line 330: You should cite this kind of samples in the Methods chapter
Reply: It was done.
Line 341: Again, you should mention and describe the leaching tests (and related procedures) in the Methods chapter
Reply: It was done.
Lines 342 and 357: IMHO this sentence (and the associated figure 12) would be better placed in the mineralogical description of the deposits in the chapter 4.
Reply: It was done.
Line 349: It seems to me that something is lacking here, as a sentence on the environmental risks you mentioned in the title...
Reply: The part of the environmental risk was re-organized.
Line 402: concentric aggregates?
Reply: Corrected.
Line 411: in studied deposits
Reply: Corrected.
Line 412. diagenetic and meta-diagenetic stages
Reply: Corrected.
Line 429: suggest that they must be considered
Reply: Corrected.
Line 433: while a smaller potential is known for
Reply: Corrected.
Line 449: lowest part, with a negative Ce anomaly,
Reply: Corrected.
Line 457: although all the other REEs are present in certain deposits, their Sc content may be insignificant
Reply: Corrected.
Line 492: ? not clear, what do you mean?
Reply: This sentence was deleted as unnecessary.
Line 496: This sentence is very long, try to split it in two or three
Reply: Re-wrirren.
Line 522: Although not directly linked to critical metals and particularly focused on Chromium, this chapter appears to be important for the overall evaluation of the possibilities of future exploitation of laterite deposits in the Balkans. However, the Chapter seems to me still a bit disconnected from those that precede, I would certainly suggest developing it more in the introduction and, above all, integrating the chapter on methods with the analytical procedures used to obtain data of environmental interest.
Reply: These chapters were re-written.
Line 565: You must mention it and adequately describe in the Methods chapter
Reply: It was added.
Many thanks once again.
Kind regards
Maria Economou-Eliopoulos
Reviewer 2 Report
Review on the manuscript entitled “Origin of critical metals in Fe-Ni laterites from the Balkan Peninsula: Opportunities and environmental risk” submitted by Maria Economou-Eliopoulos, Magdalena Laskou, Demetrios G. Eliopoulos, Ifigeneia Megremi, Sofia Kalatha and George D. Eliopoulos for possible publication in Minerals
General comments
The manuscript submitted by M. Economou-Eliopoulos et al. deals with the origin of critical metals associated with the Fe-Ni laterites from the Balkan Peninsula by using basic analytical techniques (i.e., SEM-EDS and bulk rock major and trace elements data). Overall, the paper is poorly written and the different sections are unbalanced. In this respect, the discussion should be completely rewritten, substantially shortened and more importantly strengthened by focusing on what the data are telling us and not on speculative and general statements. Equally important, the geological section which in principle should constitute the basement for this research and based on which key evidences to support the discussion section has been underestimated if not neglected. Accordingly, I suggest that the geological section should be expanded to include the geology and mineralogy of each of the major district described in the paper by providing updated geological maps, detailed mineralogical descriptions and more importantly critical cross-sections that would help the reader to see how mineralization looks like and draw regional correlations between the different investigated deposits.
For sure, the paper could be of interest for the scientific community and could serve as a database for future generations particularly in this epoch which is considered as the era of strategic metals. I am attaching herewith the edited pdf copy of the manuscript where my specific comments are annotated in the margins of the document. In summary, the manuscript requires major corrections and polishing. I recommend it for publication after a major revision. Once these major inconsistencies improved, I would be happy to reconsider my evaluation.
Comments for author File: Comments.pdf
Author Response
Reply to Reviewer 2
General comments
The manuscript submitted by M. Economou-Eliopoulos et al. deals with the origin of critical metals associated with the Fe-Ni laterites from the Balkan Peninsula by using basic analytical techniques (i.e., SEM-EDS and bulk rock major and trace elements data). Overall, the paper is poorly written and the different sections are unbalanced. In this respect, the discussion should be completely rewritten, substantially shortened and more importantly strengthened by focusing on what the data are telling us and not on speculative and general statements. Equally important, the geological section which in principle should constitute the basement for this research and based on which key evidences to support the discussion section has been underestimated if not neglected. Accordingly, I suggest that the geological section should be expanded to include the geology and mineralogy of each of the major district described in the paper by providing updated geological maps, detailed mineralogical descriptions and more importantly critical cross-sections that would help the reader to see how mineralization looks like and draw regional correlations between the different investigated deposits.
For sure, the paper could be of interest for the scientific community and could serve as a database for future generations particularly in this epoch which is considered as the era of strategic metals. I am attaching herewith the edited pdf copy of the manuscript where my specific comments are annotated in the margins of the document. In summary, the manuscript requires major corrections and polishing. I recommend it for publication after a major revision. Once these major inconsistencies improved, I would be happy to reconsider my evaluation.
Reply: According to the subject and the aim of this manuscript it is a REVIEW supplemented by new data, on the mineralizations to critical metals associated with the lateritic and bauxitic Fe-Ni deposits of the Balkan region, on the basis of their geochemical characteristics and Ni-Co-Mn-mineral chemistry. In addition, on the basis of literature data supplemented by new data, considerations are made on the environmental risks associated with the exploitation of the deposits. Therefore, it is hard for the authors to accept the comment that “the geological section which in principle should constitute the basement for this research and based on which key evidences to support the discussion section has been underestimated if not neglected”
Comments on the edited pdf copy of the manuscript
Line 16: The term weathering is more appropriate
Reply: It was corrected.
Line 17: ICP-MS analysis on which minerals?
Reply: It was clarified that we mean ICP-MS analyses of laterites.
Line 40. You should also mention that some of these deposits are of supergene origin being associated to the meteorically alterred igneous rocks.
Reply: this type of deposits is included now.
Line 50: Ni-Co (be consistent)
Reply: It was corrected.
Line 65: the ophiolitic complexes and associated fe-Ni-...
Reply: It was corrected.
Line 67: The present study focuses on.....
Reply: It was corrected
Line 68: Too long paragraph. please fragment it into short and comprehensible sentences.
Reply: This paragraph was re-written.
Line 74: Explain why grounwater composition and chrmium isotopes are important to your study?
Reply: Since oxidative weathering of Cr‐bearing ultramafic rocks facilitate the oxidation of Cr(III) into water‐soluble Cr(VI), and back again, the chromium isotopes have been applied in the investigation of contaminated groundwater. Although the details of the applied analytical methods are provided in relative references, a brief outline is given here.
Line 77: We need to have a sampling mapping
Reply: Sorry, it was corrected as laterites instead massive chromitite (it was written by mistake).
Line 86. The reader also needs to have an idea about the methodology you used and why in some cases you analyzed chrmotitites and in other cases laterite deposits as you said? Very confusing? Why in this case not analyzing the host rocks which could provide the metals you are looking for?
Reply: The used methodology of the determination of major and trace elements, including rare earth elements (REE) and platinum-group elements (PGE) in laterite samples, as well as the mineral chemistry is clear in the section 2. Methods of investigation.
With respect to the comment why in some cases you analyzed chrmotitites and in other cases laterite deposits as you said?
Reply: It was clarified (please, see previous comment) that the term chromitite was used by mistake.
Concerning the comment Why in this case not analyzing the host rocks which could provide the metals you are looking for?
Reply: It was clarified that ultramafic rocks which are potential parent rocks were analysed (Tables 3-5).
Line 93. I would move this section above and place it before Methods of investigation
Reply: This section was moved and relative references were corrected.
Line 94. Would be useful to have an idea about the tonnage, grade and past production data from these deposits.
Reply: Some information is provided here, and there is much more in the cited reference [9] for who it may concern.
Line 98: Major deposits show a complete.
Reply: corrected.
Line 106. Figure needs to be imporved and the scale enlarged as we cannot see details.
Reply: Sorry, but the provided Figure 1 is enlarged. Besides, there is the possibility to readers to enlarge it, although it is just a sketch map.
Line 117: If so this could mean that the several deposits you are describing in here formed at different times???? Are there any data on the age of mineralization
Reply: No available data for a justified opinion on this topic.
Line 137: Is this a mining company? If so please indicate it clearly for those readers that are not familiar with
Reply: It was clarified that it is a General Mining and metallurgical Company.
Line 143: which consist of .....
Reply: corrected.
Line 148: Are you talking here about primary or secondary mineralization. You should make it clear. I would suggest that firts you should tak about primary mineralization and then focus on secondary mineralization which is the scope of your study. otherwise, the reader is lost. A table summarizing the main mineralogical features of each deposit should be useful rather than long and endless sentences.
Line 157: Again, it would be preferable to get a skech that shows the weathering profile with the names of minerals within each of the identified alteration zones.
Reply: Indeed, this suggestion would provide an easier way to follow the mineralogical features of each deposit. However, it would be a repetition for this review paper since in the cited references there are available Tables presenting list of samples, the stratigraphic position, description and their mineralogical composition.
Line 150: Limonite is an ancient ambigous word that includesa melange of geothite and hematite?
Reply: it was deleted.
Line 173: Lokris and kastoria laterites
Reply: It was corrected.
Line 218: This paragraph should be kept or moved to the chemical section???
Reply: We prefer this part of the section for the Mineralogical characteristic features of chromite, as that of other minerals (Table 1).
Line 227: I could not see the logic of this comparison.
Reply: In the sentence “At the area of E. Vermio, there are abundant garnet (grossularite) and calcite, while Ni is mainly hosted in chlorite, serpentine and theophrastite (Fig5)” the association of Ni-bearing minerals with garnet and calcite is described, in order to discuss their origin in the Section of the Discussion.
Line 268: We need some figures including detailed geological map, Logs and cross-scetions in order to figure to figure out the variability of elements your are talking about.
Reply: In addition to the geological map (Fig. 2B) Schematic stratigraphic sections of the most representative laterite deposits are given now (Fig 2A).
Line 330: Please explian in few words why analyzing slags is important for studies as theorically these matallurgical residues should be deplted in most valuable elements?
Reply: thank you. The chapter of the environmental risk was re-organized and re-written.
Line 341: Why looking just for Cr(VI) and not other elements? Are there any econmic and/or scientific reasons????
Reply: It is clarified now that Cr(VI) is toxic.
Line 372: Co could also be derived from the so-called five elements (hydrothermal deposits?)
Reply: It is reported in the manuscript.
Line 435: Please give references
Reply: given
Line 444: Such REE "enrichment" could also indicate an enriched rock source???
Reply: In our opinion the relatively low REE content in the majority of the Fe-Ni-laterite deposits (sometimes lower than the detection limit of the method used) indicates an epigenetic enrichment rather than enriched rock source.
Round 2
Reviewer 2 Report
The revised version is much better improved and desserves to be published.
Author Response
Dear Editor,
Thank you very much for your comments and suggestions. All suggested corrections were made, point by point as following:
Line 25: space
Reply: corrected
Line 30: space
Reply: corrected
Lines 55-56: please, check sentence. No clear sense.
Reply: re-written.
Line 65: dot
Reply: corrected
Line 69: World's total what?
Reply: clarified, Ni
Line 91: please, try to not separe numbers
Reply: corrected
Line123: underline?
Reply: corrected.
Line 131: of
Reply: corrected
Line 174: water leaching
Reply: corrected
Line 202: thin?
Reply: corrected
Line 298: too strange
Reply: re-written.
Line 299: the gradual increase of Mn, Co and Zn outwards???
Reply: corrected
Line 321: please, revise format column 1
Reply: Table 1, the format was corrected
Line 329: a ] is lacking
Reply: corrected
Line 343: no sense
Reply: It was by mistake there, it was deleted.
Fig. 8c, Fig. 9c, Fig.12: is this r referring to R2? please check and update
Reply: No, this is r because it shows the relationship between two variables.
Fig. 10a.: why is this word here?
Reply: In the case of values >1000 we use this way, following the instructions in previous publications in the MINERALS.
Fig.12c: a ) is lacking
Reply: corrected
Line 416: which ones?
Reply: The samples analyzed in a previous study [31] are marked by the symbol * now.
Line 426: say which
Reply: the pyro-metallurgical residue (slag96 and slag14 samples). They are reported at the beginning of the sentence.
Table 6: change by Slag
Reply: corrected
Line 415: something is missing
Reply: It was re-written.
Line 435: leaching experiments have not been explained in the methodology. RAtio S:L, composition of water?, Time?
Reply: This information is provided now.
Table 7: inidcate which are from 31 and which from the present study
Reply: The samples analyzed in a previous study [31] are marked by the symbol * now.
Line 468: contain
Reply: corrected
Line 540: no sense. PLease check.
Reply: It was re-written.
Line 597: please, check. No sense.
Reply: It was re-written.
Line 605: please, check. No sense.
Reply: It was re-written.
Line 644: please check. No sense.
While Cr(III) is a required nutrient, Cr(VI9 is highly toxic, very soluble and cause.....Delete Further Cr(VI) concentrations....???
Reply: It was re-written.
Line 669: Where are they?? please refer to a table o reference.
Reply: the isotope values and reference are given now.
Line 667: In the re-working of laterites...
Reply: corrected
Many thanks one again
Kind regards
Maria Economou-Eliopoulos
