Origins of Colour of Smithsonite from Yunnan, China
Wolfgang Hofmeister
Craig Marshall
Round 1
Reviewer 1 Report
Paragraph after figure 6:
"hence, some weak absorption features were too weak to be overlooked"
This needs needs clarification.
Later on, the manuscript references Zhong about a possible role for lead:
"Lead may act as a chromophore element to give some carbonate minerals a pink to purple colour (Zhong 1990)."
This referee would take exception to this statement; the failure to find lead in the EMPA experiment supports the possibility that Pb is not a chromophore.
An ion with a filled d-orbital configuration is not going to have d-d transitions in the visible.
However, the authors simply use the Zhong reference as opposed to implying that this is an original interpretation of theirs. That is OK.
The authors characterize smithsonite from a particular deposit area in China. This is fine.
I do note that there is a web reference with spectra of blue smithsonite and a list of other references to color and spectroscopy of this phase from other than Chinese localities that came to some of the same conclusions.
Web reference:
http://minerals.gps.caltech.edu/FILES/Visible/smithsonite/Index.html
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments for author File: Comments.pdf
Author Response
Please see the attachment of the revised manuscript.
Dear Editors and Reviewer 2:
Thank you for your letter and for the comments concerning our manuscript entitled “Origins of Colour of Smithsonite from Yunnan, China” (ID: 2046464). Those comments are all valuable and very helpful for revising and improving our paper. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer's comments are as following:
- Comment:What size are the greenockite grains and how are they distributed to effect the colour?
- Reply:We appreciate for your valuable comment. We have revised the sentence to “And yellow greenockite grains scattered throughout parts of yellow smithsonites, ranging in size from sub-microscopic to 15 µm, efficiently changed the orange or yellow colour to “turkey fat” (a bright yellow variety of smithsonite resembling to turkey fat by colour and botryoidal form) yellow.”
- Comment:What is the Cu-rich inclusions like?
- Reply:Thank you for your valuable suggestion. We actually only detected the presence of copper in the EPMA test. The existence of Cu-rich inclusions is combined with the conclusions of the reference “Samouhos, M.; Zavasnik, J.; Recnik, A.; Godelitsas, A.; Chatzitheodoridis, E.; Sanakis, Y. Spectroscopic and nanoscale characterization of blue-coloured smithsonite (ZnCO3) from Lavrion historical mines (Greece). PERIOD MINERAL 2015, 84, 373-388.” We're not sure about the shape of the Cu-rich inclusions. Therefore, the more detailed description of Cu-rich inclusions is not revised in the manuscript.
- Comment: Are aurichalcite and hemimorphite detected and characterized?
- Reply:We appreciate the reviewer’s insightful suggestion. We have revised the it to “The blue-green colour change was caused by aurichalcite and hemimorphite detected by Raman test and chemical composition test.”
- Comment: Hemimorphite is usually colourless. How does it affect the blue-green colour,
- Reply:Thanks a lot for the reviewer’s comments. Hemimorphite is usually colourless. However, the composition of hemimorphite in aurichalcite-hemimorphite layers in blue smithsonite contains less than 1% copper (table below). The presence of copper gives the mineral its blue colour. Therefore, the mineral also has a certain effect on the color change.
Table 1: EDS analysis date of hemimorphite inclusions in blue smithsonite
|
No. |
17 |
21 |
|
O |
25.26 |
23.57 |
|
Si |
11.31 |
10.34 |
|
Cu |
0.78 |
0.77 |
|
Zn |
56.65 |
56.80 |
|
Total |
94.00 |
91.48 |
- Comment: The physical properties of smithsonite described in introduction require some literature.
- Reply:Thank you for pointing this out. We have added the reference about physical properties of smithsonite.
- Comment:Are these smithsonites used as material in the further studies? When yes, please declare it in the figure 2
- Reply:Thank you for your valuable suggestion.The smithsonites in figure 2 were not used for further study and only for display purposes, so no changes have been made here.
- Comment:What ores are the “home” of the elements?
- Reply:Thank you for your valuable suggestion. We have made the change. A variety of various mineral resources have been discovered in deposits from Lanping, Yunnan Province, which mostly composed of several metal ores, such as lead, zinc, silver, copper, cobalt and etc. The ore minerals include oxide minerals and sulphide minerals. The oxide minerals are usually distributed in the supergenic zones of the deposit, while the sulphide minerals include galena, sphalerite, pyrite, marcasite etc., including sulphate, carbonate, silicate of Zn and Pb, etc.
- Comment:Marine sedimentation from Upper Triassic epoch to Lower Cretaceous epoch are no ores
- Reply:Thank you foryour valuable suggestion, which is valuable for improving the accuracy of the manuscript. We have omitted the mistake.
- Comment: What does the authors mean with “anomalies”?
- Reply:Thank you for your valuable suggestion. We used this word anomalies to mean that the elements content was unusually high. But the description was not clear enough and we have removed the word.
- Comment: The geological sketch map (figure 3) is exaggerated.
- Reply: Thank you for your valuable suggestion, which is valuable for improving the accuracy of the manuscript. We have revised the map.
- Comment: Are these samples described in materials and characterization methods the samples of fig.1 and fig.2?
- Reply:Thank you for your valuable suggestion. The samples in fig. 1 and fig. 2 are for display only. Figure 4 shows the samples used for test and analysis
- Comment: Where do the samples come from and how are they looking like?
- Reply:Thank you for your valuable suggestion. From the 9 samples (figure 4), 5 representative rough samples with different colors were selected to make optical wafers for detailed testing.
- Comment: Are the samples in fig. 4 the same as those in fig.1 and fig.2?
- Reply:Thank you for pointing this out. The smithsonites in Fig. 1 and part of Fig. 2 (except for the blue faceted material) are of the same origin as the test samples in Fig. 4. And the carbonate smithsonites in Figure 2b is from the sample in Figure 4.
- Comment: In what way did the author find the granular yellow inclusions out?
- Reply:Thank you for pointing this out. These particles are not visible to the naked eye, but can be seen by magnifying them with an optical microscope (Fig. 5b) and on BSE images.
- Comment: Which samples for microscopic observation are related to the materials in the first picture?
- Reply:Thank you for pointing this out. The samples used for microscopic observation are all from Fig. 4, and there are no samples from Fig. 1 and Fig. 2
- Comment: Is these Raman tested samples displayed in the first pictures?
- Reply: Thank you for pointing this out. The samples used for Raman test are all from Fig. 4, and there are no samples from Fig. 1 and Fig. 2
- Comment: The reviewer does not agree with the existence of cassiterite in fig.9c. where is the difference to fig.9a?
- Reply:Thank you for pointing this out. Firstly, the Raman specturm of the two inclusions do not coincide at the Raman peak about 600 cm-1. The Raman peak of the inclusion in Fig. 9a is about 590 cm-1, while the peak of inclusion in Fig. 9c is around 615 cm-1. Second, there are two weak Raman peaks of the inclusions in Fig. 9c at about 500 and 690 cm-1consistent with the cassiterite Raman peaks. Finally, the colour and shape of the two inclusions (fig. 5b and 5c) are inconsistent. Therefore, the authors suggest that the two inclusions are distinct and are greenockite and cassiterite respectively.
- Comment: Are these mean values of different measuring points in the different smithsonite samples? What is the standard deviation? Or are these singles point measurements? Than they are only of very local interest?
- Reply:Thank you for pointing this out. These values in the composition test are the result of single point measurements.
- Comment:The Cd-content in YE-1 is very much lower than in BL-01, but why the authors find greenockite in YE-01? Did the authors combine Raman to find greenockite in BL-01?
- Reply:We appreciate for your valuable comment. The presence of Cd2+ions is not related to the colour of the smithsonite, which can be seen from the presence of Cd2+ ions in most samples. The morphology of greenockite inclusions does not conform to the exsolution structure. There is no clear relationship between the existence of greenockite inclusions and the amount of Cd2+ ions, although the specific cause of the presence of greenockite inclusion is not known. The greenockite inclusions are yellow, and its presence in large quantities gives the smithsonite its yellow colour. greenockite can therefore be observed in the yellow sample, while such inclusions are not present in the blue sample, which has been determined by the BSE images (Fig. 10).
- Comment: References need to completed and corrected.
- Reply:We appreciate for your valuable comment. We have revised the references.
Author Response File: Author Response.pdf
Reviewer 3 Report
This was a super interesting and well-written manuscript to read. I recommend to publish in it's current form. However, I do suggest one change. In the text of the manuscript the A1g phonon mode of smithsonite is referred to as occurring at 1039 cm-1. This should be changed to 1093 cm-1.
Author Response
Dear Editors and Reviewer 3:
Thank you for your letter and for the comments concerning our manuscript entitled “Origins of Colour of Smithsonite from Yunnan, China” (ID: 2046464). The comments are very valuable and helpful for revising and improving our paper. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer's comments are as following:
- Comment: the reviewer does suggest one change. In the text of the manuscript the A1g phonon mode of smithsonite is referred to as occurring at 1039 cm-1. This should be changed to 1093 cm-1
- Reply:We appreciate for your valuable comment. We have changed the peak in the manuscript from 1039 cm-1to 1093 cm-1.
Reviewer 4 Report
There are comments on the article:
1. In the figure of the 6th line of the IR spectra, it is very thin and have a non -core color, it is impossible to determine what spectrum to relate to a certain type of color Smithsonite, is it possible to make them brighter and increase the thickness of the spectrum line?
2. In the work, there are no studies of electronic-free centers in Smithonite, and in discussions it is indicated that the color of pink and yellow Smithsonites is connected by electronic-dying centers, without research of the material. It is advisable to additionally conduct studies of all samples by the EPR method in order to definitely be confident in nature of the coloring of Smithsonites.
3. The work does not have a clear connection of various coloring of the Smitsonite and various electronic-free centers, the conclusions have mainly general conclusions without confirming their experimental part.
4. It is advisable to conduct a thermal anneal in which many electronic-free centers are destroyed, which will indicate their nature.
Author Response
Many thanks for your kind review, please check the responce file.
Author Response File: Author Response.pdf
Reviewer 5 Report
In this nice article the authors investigated Lanping smithsonite through analysing its internal inclusion, gemmological, spectral, and compositional characteristics and explained the origins of different smithsonite colour.
In my opinion, the quality of the manuscript is high in terms of readibility, characterizations performed and results discussion.
Author Response
Many thanks for your kind support.
Reviewer 6 Report
In this paper authors investigated Lanping smithsonite through analysing its internal inclusion, gemmological, spectral, and compositional characteristics and explained the or igins of different smithsonite colour. The authors test samples by FTIR and UV-Vis. The conclusions drawn are very weak. Overall, the article is average, but such a characterization is needed for mineralogy.
Manuscript could be accepted after minor modification.
Include the scale in Figures 1 and 2.
Page 4 line 108 "to the" double space
Page 4 line 108 The website address must be as a reference
Figure 4 - The drawing caption begins with a capital letter
Figure 5 - Note that all pics are to the same scale, it is better to compare the structure.
Author Response
Many thanks for your kind review, please check the response to Reviewer 6's comments.
Author Response File: Author Response.pdf
Reviewer 7 Report
The article could be suitable for Minerals provided that some important corrections and additions will be made.
In the manuscript, only transitional elements (those substituting Zn in smithsonite or occurring in inclusions of other minerals) are considered as a cause of smithsonite colour. This conclusion is generally confirmed by chemical data. However, the role of point defects is not discussed.
In particular, blue and green (as a mixture of blue and yellow) colour of many carbonate minerals is due to the presence of (CO3)*- radical anions (see, for example, the following papers and references therein):
Shendrik, R.; Kaneva, E.; Radomskaya, T.; Sharygin, I.; Marfin, A. Relationships between the structural, vibrational, and optical properties of microporous cancrinite. Crystals. 2021, 11, 280. https://doi.org/10.3390/cryst11030280
Kaneva, E.; Shendrik, R. Radiation defects and intrinsic luminescence of cancrinite. J. Lumin. 2022, 243, 118628. https://doi.org/10.1016/j.jlumin.2021.118628
Kaneva, E.; Radomskaya, T.; Shendrik, R. J. Gemmol. 2022, 38(4), 342–351. https://doi.org/10.15506/JoG.2022.38.4.342
It is important to note that in the Raman spectra of blue and green smithsonite samples (Figure 8), very weak bands at about 1200 cm-1 are observed that can correspond to (CO3)*-.
In the Raman spectrum of yellow smithsonite a very weak band is observed at a somewhat lower wavebumber. This band should be assigned (note that Raman spectrum of white smithsonite does not contain bands in this region).
Infrared spectra (Figure 6) are of a very poor quality and are not informative. Reflectance mode is not a good choice: observed distinctions are related to reflection conditions rather than properties of the samples. Thus, the observed variations of the IR spectra are misleading. This figure (and accompanying text) must be deleted or replaced with IR spectra obtained in transmittance mode (in KBr pellets).
The assignment of a Raman spectrum of an inclusion (Figure 10) to cassiterite is obviously erroneous. Raman spectra of cassiterite published in numerous papers contain very narrow bands. The spedtrum in Figure 9 corresponds to an oxide minereal other than cassiterite (its assignment is ambiguous; in particular, it may be a pyrochlore-supergroup mineral or a Sb-oxide).
Author Response
Many thanks for your kind review, please check the response file.
Thanks.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have investigated a lot of time in reworking some parts of the manuscript; but in my opinion there is no evidence for publication in am international mineralogical journal because there is no new knowlegde on the mineral except the location in China. It would be better published in more regional or aiming at collectors journals.
Author Response
We appreciate for your valuable comment. The colour of gem-grade smithsonite varies widely, but there has not been a comprehensive analysis. The yellow, brown, and blue smithsonite from Greece has been studied. The yellow colour is due to the presence of iron ions and greenockite inclusions. The blue and green smithsonites are caused by the presence of copper. Brown smithsonite is associated with iron hydroxides. In this research, smithsonite samples with different colours from Yunnan, China were selected for study to supplement and improve to the existing conclusions on the origin of colour. For example, it is generally believed that the blue colour of the smithsonite is caused by the presence of copper. However, in our research, there are three reasons for the blue colour, which may by caused by copper or inclusions or point defects respectively. Besides, we also added the colour origin of pink smithsonite. In the discussion part, the causes of other colours mentioned in the literature were also summarized. Although the smithsonite from Yunnan, China was selected for colour origin analysis, the conclusions can also provide reference for smithsonite from other locations. We also analysed, confirmed and supplemented the inclusions in Yunnan smithsonite. For example, we found rare mineral inclusions called otavite in smithsonite. We believe that the information sharing on smithsonite of various colours from China can provide us with a lot of reliable and reference information for a deeper understanding of this mineral. All the studies in this paper focus on the gemmological and mineralogical characteristics of the smithsonite, which meet the content requirements of Minerals.
Reviewer 4 Report
This article has been corrected and can be republished.
Reviewer 7 Report
No comments
