Mineralogy and Mineral Chemistry of the Au-Ag-Te-(Bi-Se) San Luis Alta Deposit, Mid-South Peru
, Elsa Ccolqque 1, Maite Garcia-Valles 2, Arnau MartÃnez 1, Maria Teresa Yubero 1, Hernan Anticoi 1 and Nor Sidki-Rius 1
Round 1
Reviewer 1 Report
Manuscript: Mineralogy and mineral chemistry of the Au-Ag-Te-(Bi-Se) San Luis Deposit, Mid-South Peru
Authors: Pura Alfonso, et al.
General Comments:
This manuscript presents an overview of the mineralogy of the San Luis ore deposit in Peru, providing both textural analysis as well as chemical analysis of the main ore minerals. The authors present an interpretation of the sequence of mineralization that occurs in this locality and identify four stages of mineralization. The study is well done. The attached PDF file has been edited with many minor suggested changes to improve the English or correct misspelled words, which are indicated in red font. Below are a few questions and comments of a more scientific nature.
Specific comments:
lines 100-101; I was a little confused by the terms used to describe the orientation of the andesitic dykes. If the strike is N320°, then presumably the dip can not be to the southeast. Perhaps the authors are referring to the pole projection of this dipping plane that is plotting to the northwest. This would presumably make the strike something like N50°. Please clarify the wording here.
line 107; Please include a scale on the map.
line 174; The subject “it” in this sentence might be clearer if you specifically mention “pyrite”, which I assume is what you are referring to.
line 214; Please indicate if the ternary diagram is plotted on a weight % or atomic % basis. Also, correct the spelling of “porphyry” in the legend.
line 266; Again, please indicate whether the diagrams are in weight % or atomic %.
line 300; Please check that my suggested rewording has not changed the meaning of this sentence.
line 303; Please correct the spelling errors here. Chlorargyrite could be capitalized for consistency with the others.
line 317; I believe the mineral is “cuprobismutite”.
line 326; The authors proposed the presence of a Bi-Te-melt that extracts the Au and Ag from the original ore-forming hydrothermal fluid. I was wondering if the authors might be able to speculate what the bulk composition of this fluid would be and where it plots on Figures 6a and 6b? In other words, could the proportions of the minerals found in the bleb inclusions in pyrite be used to estimate the melt composition? This might be of interest to those studying ore deposit formation.
line 336; Please clarify which stage you are talking about in this sentence.
line 346; The subject “This…” is unclear; are the authors referring to the presence of a melt as indicated by the curved textures of the blebs or to the tellurium-rich nature of the melt?
line 376; Presumably the authors mean selenides rather than arsenides here in the text.
Comments for author File: 
Comments.pdf
Minor to moderate editing is needed. Please see the edited PDF file for suggested changes in grammar and spelling.
Author Response
Dear reviewer
Many thanks for your revision, that sure will improve our manuscript.
lines 100-101; I was a little confused by the terms used to describe the orientation of the andesitic dykes. If the strike is N320°, then presumably the dip can not be to the southeast. Perhaps the authors are referring to the pole projection of this dipping plane that is plotting to the northwest. This would presumably make the strike something like N50°. Please clarify the wording here.
- Sorry, it was a confusion it is notheast instead of southeast.
line 107; Please include a scale on the map.
- This was changed.
line 174; The subject “it” in this sentence might be clearer if you specifically mention “pyrite”, which I assume is what you are referring to.
- This was changed.
line 214; Please indicate if the ternary diagram is plotted on a weight % or atomic % basis. Also, correct the spelling of “porphyry” in the legend.
- The word porphyry was corrected and atomic % was added.
line 266; Again, please indicate whether the diagrams are in weight % or atomic %.
- atomic % was added.
line 300; Please check that my suggested rewording has not changed the meaning of this sentence.
- Your suggestion was OK.
line 303; Please correct the spelling errors here. Chlorargyrite could be capitalized for consistency with the others.
- This was changed.
line 317; I believe the mineral is “cuprobismutite”.
line 326; The authors proposed the presence of a Bi-Te-melt that extracts the Au and Ag from the original ore-forming hydrothermal fluid. I was wondering if the authors might be able to speculate what the bulk composition of this fluid would be and where it plots on Figures 6a and 6b? In other words, could the proportions of the minerals found in the bleb inclusions in pyrite be used to estimate the melt composition? This might be of interest to those studying ore deposit formation.
line 336; Please clarify which stage you are talking about in this sentence.
- This was clarified.
line 346; The subject “This…” is unclear; are the authors referring to the presence of a melt as indicated by the curved textures of the blebs or to the tellurium-rich nature of the melt?
- It was clarified.
line 376; Presumably the authors mean selenides rather than arsenides here in the text.
Yes, you are right, this was changed.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments for Authors:
1.- The work presented by the authors is well organised, scientifically sound and rigorously researched. It could be attractive to readers.
However, the following observations are considered necessary:
1.Abstract: The main objective of this research is not clearly stated, nor is the impact of the results obtained in the field of gold prospecting.
2.-The depth at which the samples were taken is not specified.
3.-The X-ray diffraction patterns are not shown.
4.-The genetic type of deposit is not specified in spite of the results obtained... Can it be epithermal...? High, medium or low sulphidation?
5.- Based on the results obtained, the authors are in a position to indicate which minerals belong to the primary mineral zone, the cementation or secondary enrichment zone and the oxidation zone.
6.-The data obtained in this research could provide some guidance for metallurgical concentration processes...This should be mentioned in the conclusions.
Author Response
1.- The work presented by the authors is well organised, scientifically sound and rigorously researched. It could be attractive to readers.
However, the following observations are considered necessary:
1.Abstract: The main objective of this research is not clearly stated, nor is the impact of the results obtained in the field of gold prospecting.
-The main objevtive was stated.
2.-The depth at which the samples were taken is not specified.
-It was specified: Samples were taken at different points up to 400 m depth.
3.-The X-ray diffraction patterns are not shown.
- The XRD only provided information on majority minerals, so their image is not illustrative and does not provide useful information for readers.
4.-The genetic type of deposit is not specified in spite of the results obtained... Can it be epithermal...? High, medium or low sulphidation?
- The results are not conclusive in this respect. We have shown the triangle Au-10*Ag-100*Cu, which seems to point to an epithermal origin.
5.- Based on the results obtained, the authors are in a position to indicate which minerals belong to the primary mineral zone, the cementation or secondary enrichment zone and the oxidation zone.
- Yes, we show that in the paragenetic sequence.
6.-The data obtained in this research could provide some guidance for metallurgical concentration processes...This should be mentioned in the conclusions.
- Yes, we agree; a new conclusion was added: “The results obtained in this study show that the different deposits of the Palpa-Nazca-Ocoña belt must be processed in different ways for optimum gold recovery. In the case of San Luis Alta, a pre-cyanidation treatment must be carried out prior to cyanidation.”
Author Response File: Author Response.pdf
