Diffraction Features from (101¯4) Calcite Twins Mimicking Crystallographic Ordering

Round 1

Reviewer 1 Report

This is an interesting work that certainly deserves publication in the Minerals. The author convincingly proved that the (104) domain twinning in calcite explains the c-type reflections seen in the SAED patterns. 

I wonder why the author uses plural form of pronoun ("we") when referring to his work reported in the article (lines 13, 35, and throughout of the paper)? Is there a hidden co-author?

lines 37 and 38 - the author may consider referring to the recent paper by Tollafsen et al. (2020) [in Scientific Reports | (2020) 10:8141  https://0-doi-org.brum.beds.ac.uk/10.1038/s41598-020-64751-5], in which they question the use of glendonite as a paleotemperature indicator. Moreover, they suggest that the pseudomorphic replacement of ikaite by calcite occurs by a coupled dissolution-reprecipitation mechanism at the ikaite-calcite interface.

line 220 - would it be possible that both (104) twinning and Mg/Ca ordering may simultaneously contribute to the c-type reflections?

Author Response

Dear Reviewer 1,                                                                 

I thank you for the review of my paper and I greatly appreciate your positive comments.

The revised version of the manuscript is attached. Please see my answers to your comments below.

Comment 1

This is an interesting work that certainly deserves publication in the Minerals. The author convincingly proved that the (104) domain twinning in calcite explains the c-type reflections seen in the SAED patterns. 

I wonder why the author uses plural form of pronoun ("we") when referring to his work reported in the article (lines 13, 35, and throughout of the paper)? Is there a hidden co-author?

Answer 1

I am the only author. In the revised ms I used passive voice in order to avoid confusion.

Comment 2

lines 37 and 38 - the author may consider referring to the recent paper by Tollafsen et al. (2020) [in Scientific Reports | (2020) 10:8141  https://0-doi-org.brum.beds.ac.uk/10.1038/s41598-020-64751-5], in which they question the use of glendonite as a paleotemperature indicator. Moreover, they suggest that the pseudomorphic replacement of ikaite by calcite occurs by a coupled dissolution-reprecipitation mechanism at the ikaite-calcite interface.

Answer 2

I pointed out the issue (and the suggestion) raised by the reviewer and cited the paper in the revised ms.

Comment 3

line 220 - would it be possible that both (104) twinning and Mg/Ca ordering may simultaneously contribute to the c-type reflections?.

Answer 3

In the studied pure CaCO3 sample it is not possible. The point of the paper is to emphasize the recognition of twinning and not to force Mg/Ca ordering as well as the various proposed superstructures for explaining c-type reflections.

Kind regards,

Péter Németh

Reviewer 2 Report

The presented article entitled “Diffraction features from {014} calcite twins mimicking crystallographic ordering” describes the detailed structural analysis of the CaCO₃ variety using a TEM microscope. This is quite interesting topic which could be valuable for many readers. Whole article was written in quite good English style. The scientific sense, results description and they interpretation were very well presented. Only small ambiguities that need to be completed. Taking that into account I recommend minor revision of this article.

Below you can find detailed comments:

1. It would be better if the article will be in passive rather than active voice. However, this is a reviewer's suggestion for consideration by the authors and the editor.
2. Glendonite - should be in keywords.
3. Figure 2 - the descriptions below figure are too long. I suggest give some of them, for example, in the form of a legend next to the drawings.
4. Too little accurate diagnosis of the current literature on the subject in the introduction part. The given literature is largely too old. This must be changed. In the introduction, there is no clear emphasis the innovation of the conducted research. Have other authors done similar research using the same or complementary techniques? This should be described in detail in the introduction and supported by the current literature on the subject.

Author Response

Dear Reviewer 2,                                                                 

I thank you for the review of my paper and I greatly appreciate your positive comments.

The revised version of the manuscript is attached. Please see my answers to your comments below.

Comment 1

The presented article entitled “Diffraction features from {014} calcite twins mimicking crystallographic ordering” describes the detailed structural analysis of the CaCO₃ variety using a TEM microscope. This is quite interesting topic which could be valuable for many readers. Whole article was written in quite good English style. The scientific sense, results description and they interpretation were very well presented. Only small ambiguities that need to be completed. Taking that into account I recommend minor revision of this article.

Below you can find detailed comments:

1. It would be better if the article will be in passive rather than active voice. However, this is a reviewer's suggestion for consideration by the authors and the editor.

Answer 1

I changed the text and I used passive voice.

Comment 2

Glendonite - should be in keywords.

Answer 2

I added it to the keywords.

Comment 3

Figure 2 - the descriptions below figure are too long. I suggest give some of them, for example, in the form of a legend next to the drawings.

Answer 3

I shortened the figure caption by adding legends to Fig. 3c and d.

Comment 4

Too little accurate diagnosis of the current literature on the subject in the introduction part. The given literature is largely too old. This must be changed. In the introduction, there is no clear emphasis the innovation of the conducted research. Have other authors done similar research using the same or complementary techniques? This should be described in detail in the introduction and supported by the current literature on the subject.

Answer 4

I added new text into the introduction and reviewed the current literature data. I also included a similar work (Shen et al. 2013) to mine, in which the authors had a similar conclusion while they were investigating Ca-rich dolomite using TEM and STEM. I also pointed out that my TEM images permitted the recognition of (10-14) stacking faults in calcite. 

Kind regards,

Péter Németh

Reviewer 3 Report

Dear Dr. Németh,

I have enjoyed reading your work. The topic is of importance both for fundamental mineralogy and geosciences at general. However, some issues should be addressed before publishing.

1) You constantly refer to your article "Tracing structural relicts of the ikaite-to calcite transformation in cryogenic cave glendonite", but it is just submitted, not accepted to AmMin. So, one could not check initial data.
1.1) Provide a BSE/SEM images of studied sample and an EDX/WDX spectra in order to show homogenity of your sample. Prevously, it was shown that glendones commonly consists of several carbonate phases (e.g., DOI: 10.1111/sed.12847, 10.17850/njg98-1-01), which could contain Mg, Fe, P, S, etc.
1.2.) Provide powder X-ray data of your sample in order to show, that it is pure calcite. Calcite unit-cell parameters calculation will be also very helpful. 

2) Add more details on ikaite-"glendonite" transformation (e.g., DOI 10.2110/jsr.2007.087, 2007), because it is not simple ikaite-calcite transformation. It is known (DOI 10.5194/essd-13-343-2021) that ikaite rapidly disintegrates into a mush of water and anhydrous calcium carbonate (e.g., Pauly, 1963; Bischoff et al., 1993), which can be in the form of amorphous calcium carbonate (e.g., Zou et al., 2018), vaterite (e.g., Shaikh, 1990; Ito, 1996; Ito et al., 1999;
Tang et al., 2009), aragonite (e.g., Stein and Smith, 1986; Council and Bennett, 1993), or calcite (e.g., Pauly, 1963; Bischoff et al., 1993). This data should also be included in discussion section as observed twins could result from multy-phase transformation. 

3) Add data on ikaite, monohydrocalite, aragonite and vaterite for crystal structure comparison. 

Author Response

Dear Reviewer 3,                                                                 

I thank you for the review of my paper and I greatly appreciate your positive comments that helped me to improve the manuscript.

The revised version of the manuscript is attached. Please see my answers to your comments below.

Comment 1

I have enjoyed reading your work. The topic is of importance both for fundamental mineralogy and geosciences at general. However, some issues should be addressed before publishing.

1) You constantly refer to your article "Tracing structural relicts of the ikaite-to calcite transformation in cryogenic cave glendonite", but it is just submitted, not accepted to AmMin. So, one could not check initial data.

1.1) Provide a BSE/SEM images of studied sample and an EDX/WDX spectra in order to show homogenity of your sample. Previously, it was shown that glendonites commonly consists of several carbonate phases (e.g., DOI: 10.1111/sed.12847, 10.17850/njg98-1-01), which could contain Mg, Fe, P, S, etc.

Answer 1

In the revised ms. I included a new figure (Fig. 2) that shows a BSE image and an EDX spectrum. In addition, I also added the ICP-OES data that confirmed that the studied sample was practically pure CaCO3.

Comment 2

1.2.) Provide powder X-ray data of your sample in order to show, that it is pure calcite. Calcite unit-cell parameters calculation will be also very helpful. 

Answer 1

I included the requested data in the new figure (Fig. 2) and calculated the unit cell parameters.

Comment 3

1.2.) Add more details on ikaite-"glendonite" transformation (e.g., DOI 10.2110/jsr.2007.087, 2007), because it is not simple ikaite-calcite transformation. It is known (DOI 10.5194/essd-13-343-2021) that ikaite rapidly disintegrates into a mush of water and anhydrous calcium carbonate (e.g., Pauly, 1963; Bischoff et al., 1993), which can be in the form of amorphous calcium carbonate (e.g., Zou et al., 2018), vaterite (e.g., Shaikh, 1990; Ito, 1996; Ito et al., 1999; Tang et al., 2009), aragonite (e.g., Stein and Smith, 1986; Council and Bennett, 1993), or calcite (e.g., Pauly, 1963; Bischoff et al., 1993). This data should also be included in discussion section as observed twins could result from multy-phase transformation. 

Answer 1

I greatly appreciate the reviewer’s suggestion and I included this description in the revised ms (both the introduction and discussion).

Comment 4

Add data on ikaite, monohydrocalcite, aragonite and vaterite for crystal structure comparison.

Answer 4

I included the cell parameters of ikaite, aragonite and vaterite into the revised ms. However, I preferred not to add those of monohydrocalcite because I felt that it was not related to this work.

Kind regards,

Péter Németh