The Chemical Characteristics and Metallogenic Mechanism of Beryl from Cuonadong Sn-W-Be Rare Polymetallic Deposit in Southern Tibet, China

Round 1

Reviewer 1 Report

Attached please find the comments.

Comments for author File: Comments.pdf

Author Response

Reviewers' comments:

Reviewer #1:

Review of The chemical characteristics and metallogenic mechanism of beryl from Cuonadong Sn-W-Be rare polymetallic deposit in southern Tibet, China by Wang et al. This paper reports a detailed study of the chemical composition of beryl from the Cuonadong Sn-W-Be deposit in China. The topic of the formation of beryl is interesting, and these new data are welcome. I have, however, a few concerns.

- Thank you very much for the comments and encouragement. We have revised the manuscript text, tables, figures and references as listed below.

The major concerns are as follows:

1. Some previous works have reported similar major and trace elements in the beryl of this deposit and drawn similar conclusions. What is the new viewpoint of this study that differs from previous studies? Please be more specific to enrich the geochemical significance of the study further.

- Although two scholars have done some preliminary researches on the composition of beryl in the Cuonadong deposit, they conducted a rough discussion on the element substitution mechanism of beryl of beryl and its effect on pegmatites [33,34]. However, the research on the formation mechanism of beryl is very weak. In this study, beryl crystals from pegmatitic and hydrothermal mineralization of Cuonadong deposit as the research objects, investigated by energy spectrum scanning, electron probe, LA-ICP -MS, in-situ microzone XRD. With a view to ascertaining the physical and chemical characteristics of beryl from the two types of mineralization, and discussing the Cuonadong deposit in the magmatic-hydrothermal evolution process of the rare metal Be metallogenic mechanism, which can provide evidence of the Himalayan metallogenic belt having further prospecting in rare metals.

33. Shen, J.Q.; Hu, Z.K.; Cui,S.Y.; Zhang, Y.F.; Li, E.Q.; Liang, W.;Xu, B. A Study on Beryl in the Cuonadong Be-W-Sn Polymetallic Deposit, Longzi County, Tibet, China. Crystals. 2021, 11, 777. https:// doi.org/10.3390/cryst11070777.
34. Tao X.Y.; Xie L.; Wang R. C.; Zhang R. Q.; ,Hu H.; ,Liu C. Mineralogical characteristics of beryl: A case study of the beryls from Cuona and Qomolangma district in Himalaya. Journal of Nanjing University (Nature Science) 2020,56,815-829. [CrossRef]
35. Introduction: There are only several shallow remarks about elemental Be and this deposit. That's not enough. More relevant research progress and scientific issue need to be involved. What is the primary controversy or uncertainty about Be migration and precipitation mechanism?

-We have added research progress on the key factors of magmatic-hydrothermal transition in granitic systems, including temperature, pressure, melt composition, fractionation, and the volatile components such as B, P, and F. For details, see Section 1. Introduction.

3. The information of hydrothermal fluids (e.g., temperature, chemical composition, etc.) in the Cuonadong deposit must be specific. It is essential for your arguments. The complex state and behavior of Be in fluid indicate that Be is transported as fluoride or fluoride-carbonate complexes in low-temperature hydrothermal fluid (below 300℃). This means that magmatic-hydrothermal fluid with high-temperature does not have the significant ability to transport Be (see Wood, 1992).

- We added the significance of chemical composition of beryl effecting on the magmatic-hydrothermal transition in granitic systems in the Section 5.2. Besides, the information of hydrothermal fluids (e.g., temperature, chemical composition, etc.) in the Cuonadong deposit, we referenced the previous research results, such as [28] and [72,73]. Based on that, we reviewed and discussed the migration patterns of Be. For details, see Section 5.3 Metallogenic mechanism.

28. Cao, H.W.; Li, G.M.; Zhang, R.Q.; Zhang, Y.H.; Zhang, L.K.; Dai, Z.W.; Zhang, Z.; Liang, W.; Dong, S.L.;Xia, X.B.; Genesis of the Cuonadong tin polymetallic deposit in the Tethyan Himalaya: Evidence from geology, geochronology, fluid inclusions and multiple isotopes. Gondwana Research.2021,92,72-101. [CrossRef]
29. Dai, Z.W. Study on Mineralization of the Cuonadong Be-Sn-W Polymetallic Deposit, Tibet, China. Ph.D.Thesis, Chengdu University of Technology, China, 2020. [CrossRef]
30. Dai, Z.W.; Li, G.M.; Ding, J.; Zhang, L.K.; Cao, H.W.; Zhang, Z.; Liang, W. Chemical and Boron Isotopic Composition, and Significance of Tourmaline from the Cuonadong Tourmaline Granite, Tibet. Earth Sci. 2019,44,1849-1859.
31. The writing style and grammar require more careful scrutiny by native English speakers. Please check the English after revision. Some professional words have been misused.

- The English has been polished by a geoscience expert from a professional language-editing company once again.

Some minor changes are suggested below:

1. Line 362-363: You should state what kind of complex plays a key role in the migration of Be in Cuonadong deposit.

-The microthermometry results of fluid inclusions show that the temperature of ore-forming fluid of hydrothermal vein orebodies range from 197 ℃ to 343℃ [28]. Under such mineralization condition, beryllium mostly exists in the form of fluoride, chloride, and complexes containing fluorine or chlorine, while beryllium tends to be migrated as beryllium carbonate complexes if the activity of fluorine in the solution is low and the activity of carbonic acid is high [74,75]. There are many wide fluorite veins in Cuonadong mining area [17,28], indicating that the ore-forming fluid is extremely rich in fluorine. Therefore, it can be inferred that beryllium is most likely be transported as beryllium fluoride (BeF) or fluoride complex ions (e.g., [BeF₄]²⁻ ), in this area.

17. Xia, X.B.; Li, G.M.; Zhang, L.K.;Zhang,Z.;Cao,H.W.;Liang,W. Geological characteristics of and prospecting strategy for the Xianglin Be-Sn polymetallic ore deposit in the Cuonadong gneiss dome in southern Tibet. Earth Sci. Front. 2022, 29,093-106. [CrossRef]
18. Cao, H.W.; Li, G.M.; Zhang, R.Q.; Zhang, Y.H.; Zhang, L.K.; Dai, Z.W.; Zhang, Z.; Liang, W.; Dong, S.L.;Xia, X.B.; Genesis of the Cuonadong tin polymetallic deposit in the Tethyan Himalaya: Evidence from geology, geochronology, fluid inclusions and multiple isotopes. Gondwana Research.2021,92,72-101. [CrossRef]
19. Wood, S.A. Theoretical prediction of speciation and solubility of beryllium in hydrothermal solution to 300℃ at saturated vapor-pressure-Application to Bertrandite Phenakite Deposits. Ore Geol. Rev. 1992,7, 249–278.
20. Long, Z.Y.; Yu, X.Y.; Zheng, Y.Y. Ore formation of the Dayakou emerald deposit (Southwest China) constrained by chemical and boron isotopic composition of tourmaline. Ore Geo. Rev. 2021, 135, 104208.

2. Line 363-365: Supercritical fluid is a possible assumption. However, I suggest the authors soften their language and present it as a plausible hypothesis.

-This information has been revised. The viewpoint of this paper has been added in the “Section 5.3 Metallogenic mechanism”.

Due to the intrusion of pegmatite magma into the surrounding rock, there is a signifi-cant temperature difference between the two, resulting in undercooling of the melt-liquid phase and a decrease in the solubility of rare metal minerals[69].Meanwhile, some minerals riching in flux components (such as fluorite, tourmaline, and apatite) crystallize[73], leading to a great decrease in contents of flux components such as F, B, and P in the ore-forming system and Beryl-Ⅰcrystallization.

69. Tang, Y.; Qin, S.X.; Zhao, J.Y.; Lü, Z.H.; Liu, X.Q.; Wang, H.; Chen, J.Z.; Zhang, H. Solubility ofrare metals as a constraint on mineralization of granitic pegmatite. Earth Sci. Front. 2022, 29, 081-092. [CrossRef]

University of Technology, China, 2020. [CrossRef]

73. Dai, Z.W.; Li, G.M.; Ding, J.; Zhang, L.K.; Cao, H.W.; Zhang, Z.; Liang, W. Chemical and Boron Isotopic Composition, and Significance of Tourmaline from the Cuonadong Tourmaline Granite, Tibet. Earth Sci. 2019,44,1849-1859.

3. Line 403-407: This is a risky statement. The authors should present key evidence in favor of this speculation.

- In this study, beryl occurs in the pegmatites and hydrothermal vein ore bodies in the Cuonadong mining area indicates that beryllium mineralization is characterized by magmatic-hydrothermal transition. Some granitic rare metal deposits in South China have the similar characteristics, that is, the pegmatic crusts are usually developed on the top of the granitic rock mass, while hydrothermal mineralization occurs at the sur-roundings of the rock mass, and the hydrothermal mineralization pattern is closely re-lated to the surrounding rocks [10,78,79]. A large number of leucogranite similar to the Cuonadong leucogranite are developed in the Himalayas, and the Tethys Himalayan sedimentary sequence is mainly a set of clastic rocks and carbonate rocks originating from passive Indian continental margin [32]. In conclusion, there is furtherly great potential to prospect the pegmatite, skarn and other hydrothermal-vien rare metal deposits related to leucogranite in the Himalayas.

10. Wang, R.C.; Che, X.D.; Zhang, W.L.; Zhang, A.C.; Zhang, H. Geochemical evolution and late re-equilibration of Na-Cs-rich beryl from the Koktokay #3 pegmatite (Altai, NW China). Eur. J. Mineral. 2009, 21, 795–809. [CrossRef]
11. He, C.T.; Qin, K.Z.; Li, J.X.; Zhou, Q.F.; Zhao J.X.; Li G.M. Preliminary study on occurrence status of beryllium and genetic mechanism in Cuonadong tungsten-tin-beryllium deposit, eastern Himalaya. Acta Petrol. Sinica. 2020,36(12):3593-3606. [CrossRef]
12. Rao, C,; Wang, R.;C.; and Hu, H,. Electron-Microprobe Compositions and Genesis of Beryls from the Nanping No. 31 Granitic Pegmatite (Fujian Province, Southeastern China). Geological Journal of China Universities 2009,15,496-505.
13. Wu, F. Y.; Liu, Z. C.; Liu, X. C. Himalayan leucogranite: Petrogenesis and implications to orogenesis and plateau uplift. Acta Petrol. Sinica.2015, 31, 1-36.

4. Metallogenic mechanism: You mainly described a possible genetic model of the Cuonadong deposit. But the explanation of the metallogenic mechanism is far from enough. If the scientific problem this paper wants to solve is the metallogenic mechanism of beryl, more details need to be elaborated. What are the migration mechanisms of beryllium in melt and hydrothermal fluid? What process triggered the destabilization of Be complexes and subsequent the beryl precipitation? I would suggest here that you add a few references to support a hydrothermal tansport and deposition of beryl, for instance:

Fluid boiling and fluid-rock interaction as primary triggers for emerald deposition: Insights from the Dayakou emerald deposit (China). Ore Geology Reviews 139:104454.

Ore formation of the Dayakou emerald deposit (Southwest China) constrained by chemical and boron isotopic composition of tourmaline. Ore Geology Reviews 135:104208.

-Thank you very much for your constructive suggestions, and we have carefully read these two papers recommended by you, and obtained more papers on beryllium migration mechanism. To clarify the spatial and genetical relationship among the processes of mineralization, a detailed metallogenic model diagram has been added in the revised draft as shown in Fig. 12. For details, see Section 5.3 Metallogenic mechanism.

5. Conclusion: There are only mineralogical conclusions but not metallogenic mechanisms. What is the intention of this study?

- We have added the conclusions of metallogenic mechanisms, which are, (1) The precipitation of Beryl-Ⅰis mostly caused by the emplacement of highly fractionated magma containing Be to the top of rock mass or surrounding rock, the melt-fluid undercooling and the crystallization of volatile minerals (such as tourmaline and fluorite). (2) Beryl-Ⅱ precipitates owing to the ore-forming fluid mixing with the hydrothermal water and cooling, and large amounts of crystallization of volatile minerals (mainly fluorite).

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

Your manuscript presents the results of a study of beryl in the magmatic-hydrothermal polymetallic deposit of Cuonadong in Tibet. Though a combination of geochemical and structural characterisation methods, you compare beryl in different mineralisation contexts: type I in tourmaline-bearing pegmatites, and type II in (later) hydrothermal cassiterite-bearing veins.

After a critical read, I must report that there are various inconsistencies and important weaknesses in the manuscript:

1. The discussion is loosely framed in the thematic of magmatic-hydrothermal transition. There is a lack of contextualisation of this study both in the introduction and in the discussion based on what is known from pegmatites as key elements of magmatic-hydrothermal transition in granitic systems. I think a review of recent work in this thematic would be beneficial.
2. The textural and mineralogical description of the two mineralisation types where beryl was studied are quite incomplete. For example, it is unclear how much beryl is present in either pegmatite or hydrothermal veins, or how hydrothermal processes are identifiable in the surrounding rocks.
3. The quality of the EPMA results does not seem satisfactory. Totals are really low, and no explanation is provided on why results can be trusted. Moreover, only 3 samples are presented. As a reviewer it is important to have all data for the 33 analyses, and also later for the scientific community it is essential to have access to the full data.
4. The preference for Li measured with LA-ICP-MS instead of calculated Li is not totally clear. It is not stated in the methodology if an internal standard (e.g. Al) was used to reach correct quantification by LA-ICP-MS. Results for e.g. Cs seem to vary a lot between EPMA and LA-ICP-MS, and this is not addressed.
5. A lot of the discussion relies on the negative correlation between Li and Be. A perfect correlation exists because Be was calculated after Li. This cannot be used to infer any substitution systematics.
6. Although a qualitative genetic model is proposed relating the two types of polymetallic mineralisation, and therefore implying a magmatic-hydrothermal transition from leucogranites(?) up until hydrothermal Sn-veins, it is solely based on Be systematics, virtually ignoring to discuss other few key elements such as Sn, Cs and Mg. The role of differentiation from leucogranites to pegmatites is not properly explained. Also, the skarn is mentioned at the beginning but completely left out of the genetic model.

Other problems to pay attention to are the lack of consistency in nomenclature (e.g. melt-hydrothermal, magma-hydrothermal, magmatic-hydrothermal are all used), the readability of figures (e.g. Fig. 3 and Fig. 10), the lack of consistency between text and referenced figures (e.g. mentions to Fig. 4) and the numerous typos that at times impede the reader from understanding the content of the text.

I therefore suggest you review more literature information, reassess the quality of your numbers, and improve your discussion to reach a publishable manuscript.

Best regards.

Some specific comments:

Line 38: what is the 1 after beryllium?

Line 43: a ")" is missing

Line 56 (and others): in magmatic contexts I believe “crystals” is more appropriate than “grains”

Line 70: leucogranites instead of “pale”?

Line 77: pyroxenite is not a mineral

Line 78: limonite is not a rare-metal mineral; lepidolite and spodumene are different minerals

Line 98: shear instead of “sheat”

Line 132: related how? Spatially, genetically…?

Line 143: strange description, and none of these minerals is shown in Fig 4b

Line 146: remove “alterations”

Line 150: as a late-stage fluid?

Line 155: Analytical

Line 162: are you sure it was a CAMECA?

Line 193: no element measured with EPMA used as internal standard?

Line 206-216: missing here is to state which ones are types I and II that comes up after in the text

Line 213: this is not visible in Fig 5c

Line 232: higher or lower?

Line 256: mapping was only done for 1 crystal? Please specify

Fig. 7: what are the black dots? And what are the scales for the different elements?

Line 288: not what is shown in Fig 8

Fig 8: R₂O apfu? That cannot be right

Line 309: reference not following the style of the rest of the paper

Line 346: fraction of what?

Line 365-373: seems a bit unnecessary and repeats what is in 2 phrases before

Line 378: unclear: they become unstable and decompose?

Line 391-392: Not that obvious to the reader... Support your claim referring to the text/figures

Conclusions: could be expanded to contextualise the characteristics found in the overall knowledge about deposits in the magmatic-hydrothermal transition

Author Response

Reviewers' comments:

Reviewer #2:

Your manuscript presents the results of a study of beryl in the magmatic-hydrothermal polymetallic deposit of Cuonadong in Tibet. Though a combination of geochemical and structural characterisation methods, you compare beryl in different mineralisation contexts: type I in tourmaline-bearing pegmatites, and type II in (later) hydrothermal cassiterite-bearing veins.After a critical read, I must report that there are various inconsistencies and important weaknesses in the manuscript:

- We have revised the manuscript text, tables, figures and references based on your valuable comments.

1.The discussion is loosely framed in the thematic of magmatic-hydrothermal transition. There is a lack of contextualisation of this study both in the introduction and in the discussion based on what is known from pegmatites as key elements of magmatic-hydrothermal transition in granitic systems. I think a review of recent work in this thematic would be beneficial.

- We have added research progress on the key factors of magmatic-hydrothermal transition in granitic systems, including temperature, pressure, melt composition, fractionation, and the volatile components such as B, P, and F. Meanwhile, the significance of chemical composition of beryl on the magmatic-hydrothermal transition in granitic systems and the migration patterns of Be are reviewed and discussed. For details, see ‘1. Introduction’ and ‘5.3 Metallogenic mechanism’.

2.The textural and mineralogical description of the two mineralisation types where beryl was studied are quite incomplete. For example, it is unclear how much beryl is present in either pegmatite or hydrothermal veins, or how hydrothermal processes are identifiable in the surrounding rocks.

-We have added the information about mineralization characteristics in the Section “2.2.2 Mineralization characteristics”. Besides, we described the occurrence of the two types of beryl in the Section “4.1. Occurrence”.

Beryl is the main beryllium-bearing mineral in the pegmatites, with crystals up to 10 cm and colors ranging from blue-green to pale green, which co-exists with quartz, plagioclase, K-feldspar, muscovite, tourmaline and fluorite (Figure 4a). The content of beryl in pegmatite dikes is not uneven, and the scale of individual veins is small, which is not easy to be evaluated [17].

The latest exploration results show that 11 new hydrothermal vein Sn-W-Be ore bodies have been discovered in the Xianglin area, among which one main ore body (No. Z6 orebody) has the predicted potential resources of Sn 73,800 tons @1.75%, WO₃ 19,900 tons @0.36% and BeO 3100t @ 0.14% [51]. Beryllium occurs mainly in beryl. In addition, previous researchers have revealed extensive hydrothermal alteration in the surrounding rocks, such as greisenization, albitization, silicification, fluoritization and pyritization[17,28].

17.Xia, X.B.; Li, G.M.; Zhang, L.K.;Zhang,Z.;Cao,H.W.;Liang,W. Geological characteristics of and prospecting strategy for the Xianglin Be-Sn polymetallic ore deposit in the Cuonadong gneiss dome in southern Tibet. Earth Sci. Front. 2022, 29,093-106. [CrossRef]

28.Cao, H.W.; Li, G.M.; Zhang, R.Q.; Zhang, Y.H.; Zhang, L.K.; Dai, Z.W.; Zhang, Z.; Liang, W.; Dong, S.L.;Xia, X.B.; Genesis of the Cuonadong tin polymetallic deposit in the Tethyan Himalaya: Evidence from geology, geochronology, fluid inclusions and multiple isotopes. Gondwana Research.2021,92,72-101. [CrossRef]

51.Li,G.M.; Zhang, L.K.; Zhang,Z.; Xia, X.B.; Liang,W.;Hou,C.Q. New exploration progresses, resource potentials and prospecting targets of strategic minerals in the southern Qinghai-Tibet Plateau. Sedimentary Geol. and Tethyan Geol. 2021, 41,351-360. [CrossRef]

3.The quality of the EPMA results does not seem satisfactory. Totals are really low, and no explanation is provided on why results can be trusted. Moreover, only 3 samples are presented. As a reviewer it is important to have all data for the 33 analyses, and also later for the scientific community it is essential to have access to the full data.

- One beryl crystal from pegmatite and two from hydrothermal vein were analyzed in this study. The data in this study are basically similar to the chemical composition characteristics of beryl crystals in typical magmatic-hydrothermal beryllium rare metal deposits at home and abroad[10,11,34,56]. Thus, it does not affect the main conclusions of this paper. In the future researching work, we will add more test data to obtain more reliable conclusions.  Considering the layout of this manuscript, we have selected representative data for inclusion in the text. At the meanwhile, we have uploaded the complete test data to the system as a supplementary file together with the revised manuscript for your review.

10.Wang, R.C.; Che, X.D.; Zhang, W.L.; Zhang, A.C.; Zhang, H. Geochemical evolution and late re-equilibration of Na-Cs-rich beryl from the Koktokay #3 pegmatite (Altai, NW China). Eur. J. Mineral. 2009, 21, 795–809. [CrossRef]

11.Zhou Q.F.; Qin, K.Z.; Tang, D.M; et al. Mineralogy of the Koktokay No.3 Pegmatite, Altai, NW China: Implications for Evolution and Melt-Fluid Processes of Rare-metalpegmatites. Eur. J. Mineral. 2015, 27(3):433-457. [CrossRef]

34.Tao X.Y.; Xie L.; Wang R. C.; Zhang R. Q.; ,Hu H.; ,Liu C. Mineralogical characteristics of beryl: A case study of the beryls from Cuona and Qomolangma district in Himalaya. Journal of Nanjing University (Nature Science) 2020,56,815-829. [CrossRef]

56.Sardi, F.G.; Heimann, A. Pegmatitic beryl as indicator of melt evolution: example from the Velasco district, Pampeana pegmatite province, Argentina, and review of worldwide occurrences. Can. Mineral. 2014, 52, 809-836.

4.The preference for Li measured with LA-ICP-MS instead of calculated Li is not totally clear. It is not stated in the methodology if an internal standard (e.g. Al) was used to reach correct quantification by LA-ICP-MS. Results for e.g. Cs seem to vary a lot between EPMA and LA-ICP-MS, and this is not addressed.

- Normalization was performed using electron probe measurements of ²⁹Si in beryl as an internal standard to correct for LA-ICP-MS instrument drift. That has been added. Therefore, this paper mainly adopts the scientific data obtained by EPMA to discuss the chemical composition characteristics of the beryls.

5.A lot of the discussion relies on the negative correlation between Li and Be. A perfect correlation exists because Be was calculated after Li. This cannot be used to infer any substitution systematics.

- This information has been deleted in the revised version.

6.Although a qualitative genetic model is proposed relating the two types of polymetallic mineralisation, and therefore implying a magmatic-hydrothermal transition from leucogranites(?) up until hydrothermal Sn-veins, it is solely based on Be systematics, virtually ignoring to discuss other few key elements such as Sn, Cs and Mg. The role of differentiation from leucogranites to pegmatites is not properly explained. Also, the skarn is mentioned at the beginning but completely left out of the genetic model.

- We have added the indicative significance of key elements such as Na, Cs, Fe, Mg to the process of magma-hydrothermal evolution, in the "Section 5.2. Classification" for details. To clarify the spatial and genetical relationship among the processes of mineralization, a detailed metallogenic model diagram has been added in the revised draft as shown in Fig. 12.

# Other problems to pay attention to are the lack of consistency in nomenclature (e.g. melt-hydrothermal, magma-hydrothermal, magmatic-hydrothermal are all used), the readability of figures (e.g. Fig. 3 and Fig. 10), the lack of consistency between text and referenced figures (e.g. mentions to Fig. 4) and the numerous typos that at times impede the reader from understanding the content of the text.

-We have revised the “melt-hydrothermal” and “magma-hydrothermal” to “magmatic-hydrothermal”. And in the revised draft, the consistency between text and the referenced figure has been comprehensively revised. For example, Figs. 3, 10.

# I therefore suggest you review more literature information, reassess the quality of your numbers, and improve your discussion to reach a publishable manuscript.

-We are very grateful for your helpful and constructive comments. We have revised the text, tables, figures and references, which is a completely new version compared to the previous one. And we hope that the revised manuscript will be considered for publication in Minerals.

# Some specific comments:

1.Line 38: what is the 1 after beryllium?

- This sentence has little relevance to the research topic of this manuscript, so we have deleted it.

2.Line 43: a ")" is missing

-We added the ")".

3.Line 56 (and others): in magmatic contexts I believe “crystals” is more appropriate than “grains”

-We totally agree with your suggestion. And we have replaced all the "beryl grains" in this manusript with "beryl crystals".

4.Line 70: leucogranites instead of “pale”?

- We have revised all the "pale granites" to "leucogranites".

5.Line 77: pyroxenite is not a mineral

- We totally agree with your suggestion, so we have removed it.

6.Line 78: limonite is not a rare-metal mineral; lepidolite and spodumene are different minerals

- As limonite indeed is not a rare-metal mineral, we removed it. We revised “iron- lepidolite- spodumene” to “iron- lepidolite”.

7.Line 98: shear instead of “sheat”

-We have revised "sheat" to" shear ".

8.Line 132: related how? Spatially, genetically…?

- The pegmatite Be orebody is spatially related to muscovite granite. Here, we aim to describe the spatial relationship between pegmatite Be ore and muscovite granite. In fact, in "Section 5.3 Metallogenic mechanism " we discussed the genetical connection between the two.

9.Line 143: strange description, and none of these minerals is shown in Fig 4b

-We have replaced the original Fig.4b with a photograph of typical mineral assemblage for skarn mineralization.

10.Line 146: remove “alterations”

-We have removed “alterations”.

11.Line 150: as a late-stage fluid?

-We didn’t find “as a late-stage fluid” in Line 150.

12.Line 155: Analytical

- That was a silly spelling error. We have revised it to “Analytical”.

13.Line 162: are you sure it was a CAMECA?

- The instrument model used by EPMA in this study is a JEOL JXA-8230 electron microprobe.

14.Line 193: no element measured with EPMA used as internal standard?

- Normalization was performed using electron probe measurements of ²⁹Si in beryl as an internal standard to correct for instrument drift. That has been added.

15.Line 206-216: missing here is to state which ones are types I and II that comes up after in the text

-We have added that Beryl-Ⅰis the beryl in from pegmatite ore body and Beryl-Ⅱ is the beryl from the hydrothermal veins ore body.

16.Line 213: this is not visible in Fig 5c

- The previous statement was inaccurate. We have revised it. “…BSE images of these beryl particles show homogeneous structure and locally develop the altered edges, of which is metasomatized by quartz, muscovite, K-feldspa, albite along the edges or fissures(Figure 5 b,c)”.

17.Line 232: higher or lower?

- Li content in beryl calculated by EPMA (0.04-0.87wt.%) is significantly lower than that directly determined by LA-ICP-MS (1.23-2.48wt.%).

18.Line 256: mapping was only done for 1 crystal? Please specify

-By the microscopic observation, we found that the beryl produced only in the hydrothermal vein-type orebodies (Beryl-II) generally developed a ring structure. In order to further study the compositional characteristics of these rings, we selected one grain of Beryl-II with a typical ring structure for LA-ICP-MS Mapping. The result of Beryl-II's mapping shows that the development of these complex zonings are mainly caused by the differences among the contents of elements such as Na, Cs, Be, Al, Cr, and As. It probably reflects the unbalanced crystallization environment and the heterogeneity of ore-forming fluids, indicating that extensive fluid immiscibility and metasomatism has occurred in the metallogenic system [72], and it has obviously undergone the superimposed transformation of later ore-forming fluids, such as strong alkaline metasomatism in the late period of beryl mineralization [10,76]. In the further research, we will add more test data to obtain more reliable conclusions.

10. Wang, R.C.; Che, X.D.; Zhang, W.L.; Zhang, A.C.; Zhang, H. Geochemical evolution and late re-equilibration of Na-Cs-rich beryl from the Koktokay #3 pegmatite (Altai, NW China). Eur. J. Mineral. 2009, 21, 795–809. [CrossRef]
11. Dai, Z.W. Study on Mineralization of the Cuonadong Be-Sn-W Polymetallic Deposit, Tibet, China. Ph.D.Thesis, Chengdu University of Technology, China, 2020. [CrossRef]
12. Rao, C.; Wang, R.C.; Hu, H. Paragenetic assemblage of beryllium silicates and phosphates from the Nanping granite pegmatite dyke; Fujian province southeastern China. Can. Mineral. 2011, 49, 1175–1187. [CrossRef]

19.Fig. 7: what are the black dots? And what are the scales for the different elements?

- The black dots on the backscaterred-electron image(a) may be some impurities unrelated to the beryl-II grain, because they didn’t show any obvious compositional variation by the result of LA-ICP-MS mapping. And we added the scales for the different elements.

20.Line 288: not what is shown in Fig 8

- Fig. 8 was incorrect,  so we have removed it.

21.Fig 8: R2O apfu? That cannot be right

- Fig. 8 was incorrect, so we have removed it.

22.Line 309: reference not following the style of the rest of the paper

- The mistake has been corrected.

23.Line 346: fraction of what?

- We have revised “fraction” to “fractionation”.

24.Line 365-373: seems a bit unnecessary and repeats what is in 2 phrases before

- We totally agree with your suggestion, so we have deleted it.

25.Line 378: unclear: they become unstable and decompose?

- This information has been deleted in the revised version.

26.Line 391-392: Not that obvious to the reader... Support your claim referring to the text/figures

- This information has been revised. The viewpoint of this paper has been added in the revised version. For details, see Section 5.3 Metallogenic mechanism.

27.Conclusions: could be expanded to contextualise the characteristics found in the overall knowledge about deposits in the magmatic-hydrothermal transition

- We have reorganized the conclusions drawn from this study, as follows:

(1) In terms of composition, beryls in the Cuonadong deposit are alkaline beryls, among which beryl-I is Li-Cs beryl and beryl-II consists of Na and Na-Li beryl. Structurally, they are t-beryls. It indicates that beryl has experienced the magmatism to hydrothermal alkali-metasomatism in the late stage of pegmatic magmatism during the formation.

(2)The mechanism of element substitution in Bery-Ⅰincludes (Na,Cs)Li□_-1Be_-1 channel-tetrahedral substitution, (Na,Cs)Fe²⁺□_-1Al_-1 channel-octahedral substitution and NaCs_-1 the mutual substitution of alkali metal ions in ‘channel’, whereas that in Beryl-Ⅱ consists of NaLi□_-1Be_-1 channel-tetrahedral substitution and Na(Fe²⁺,Mg)□_-1Al_-1 channel-octahedral substitution.

(3)The precipitation of Beryl-Ⅰis mostly caused by the emplacement of highly fractionated magma containing Be to the top of rock mass or surrounding rock, the melt-fluid undercooling and the crystallization of volatile minerals (such as tourmaline and fluorite).

(4) Beryl-Ⅱprecipitates owing to the ore-forming fluid mixing with the hydrothermal water mixing and cooling, and large amounts of crystallization of volatile minerals (mainly fluorite).

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I have checked the revised version and seems it much improved and I agree for publishing  in the high quality Journal.

Author Response

We sincerely appreciate your patience and effort in reviewing our manuscript and providing significant comments and suggestions that have greatly improved this paper.

Reviewer 2 Report

Dear authors,

Thank you for your clarifications and changes/additions to the text addressing my points of concern on the previous version of your manuscript. I believe now the relevance of your study is clearer and the results are discussed more critically. I still have some minor suggestions to improve clarity that came up while going through your text again and I list them below. I wish you a lot of success on your future research investigating these interesting rocks.

Line 11: vein

Line 16: noticeable instead of obvious would sound better

Lines 17-18: under high-differentiation magmatic conditions?

Line 23: pegmatitic

Lines 26 and 29: volatile-bearing minerals

Line 27: has further migrated

Line 65: so it is commonly present in granitic residual melts and enriched in evolved granites and granitic pegmatites

Lines 68-71: It is a bit unclear what is meant here. What is the peraluminous beryllium metallogenetic system, and how it can be subdivided in three types? Both granites and pegmatites are within a magmatic-hydrothermal transition system. I think maybe it should be rephrased to: “which is mostly present in peraluminous systems and can be formed at multiple stages of the magmatic-hydrothermal transition.”

Line 109: incomplete instead of very weak

Line 198-199: a) ‘is evenly distributed’ instead of ‘not uneven’? b) add approximate indication of how small veins are (a few cm? tens of cm?) c) clarify what is not easy to be evaluated

Line 201: dominant

Line 202-203: are vesuvianite, albite and garnet beryl isomorphs? Seems a bit strange. Would it be that Be occurs in these minerals through substitutions?

Line 218: muscovite granites?

In analytical methods: here you should state explicitly how many crystals were analysed in this study, and how many data points come from each crystal. This will make the info on Tables 1 and 2 clearer to the reader.

Lines 315-316: numbers mentioned and phrase do not match.

Line 330: implies

Line 340: elements

Lines 376-390: typos and some misused words here make this paragraph very confusing, please revise carefully.

Line 505: two-mica

Line 529: what is meant by dissolution of magmatic fluid?

Line 598: Beryl occurrences in

Author Response

Thank you for your clarifications and changes/additions to the text addressing my points of concern on the previous version of your manuscript. I believe now the relevance of your study is clearer and the results are discussed more critically. I still have some minor suggestions to improve clarity that came up while going through your text again and I list them below. I wish you a lot of success on your future research investigating these interesting rocks.

-We are very grateful for your patience and effort in reviewing our manuscript. We have revised the manuscript based on your valuable comments and suggestions.

1. Line 11: vein

-We have revised the silly typo.

2. Line 16: noticeable instead of obvious would sound better

- We have replaced ‘obvious’ with ‘noticeable’.

3. Lines 17-18: under high-differentiation magmatic conditions?

- We have revised it to be “…under high-differentiation magmatic conditions”.

4. Line 23: pegmatitic

- We have revised it to be “pegmatitic”.

5. Lines 26 and 29: volatile-bearing minerals

- We have revised it to be “volatile-bearing minerals”.

6. Line 27: has further migrated

- We have revised it to be “…has further migrated”.

7. Line 65: so it is commonly present in granitic residual melts and enriched in evolved granites and granitic pegmatites

- We have revised it to be “…so it is commonly present in granitic residual melts and enriched in evolved granites and granitic pegmatites”.

8. Lines 68-71: It is a bit unclear what is meant here. What is the peraluminous beryllium metallogenetic system, and how it can be subdivided in three types? Both granites and pegmatites are within a magmatic-hydrothermal transition system. I think maybe it should be rephrased to: “which is mostly present in peraluminous systems and can be formed at multiple stages of the magmatic-hydrothermal transition.”

- We totally agree with your view, and we have revised it to “…which is mostly present in peraluminous systems and can be formed at multiple stages of the magmatic-hydrothermal transition.”

9. Line 109: incomplete instead of very weak

- We have replaced “very weak” with “incomplete”.

10. Line 198-199: a) ‘is evenly distributed’ instead of ‘not uneven’? b) add approximate indication of how small veins are (a few cm? tens of cm?) c) clarify what is not easy to be evaluated

- The content of beryl in pegmatite dikes is not unevenevenly distributed, and the scale of individual veins is tens of centimeters to a few meters, which has not yet been evaluated which is not easy to be evaluated [14,17].

14. Li, G.M.; Zhang, L.K.; Jiao, Y.J.; Xia, X.B.; Dong, S.L.; Fu, J.G.; Liang, W.; Zhang, Z.; Wu, J.Y.; Dong, L.; Huang, Y. First discovery and implications of Cuonadong superlarge Be-W-Sn polymetallic deposit in Himalayan metallogenic belt, souther Tibet. Mineral Deposits. 2017, 36, 1003–1008. [CrossRef]
15. Xia, X.B.; Li, G.M.; Zhang, L.K.;Zhang,Z.;Cao,H.W.;Liang,W. Geological characteristics of and prospecting strategy for the Xiang

11. Line 201: dominant

-We have revised the typo.

12. Line 202-203: are vesuvianite, albite and garnet beryl isomorphs? Seems a bit strange. Would it be that Be occurs in these minerals through substitutions?

- We have revised it to be “…Beryllium mainly occurs in silicate minerals such as vesuvianite, albite and garnet, through element substitutions”.

13. Line 218: muscovite granites?

- We have revised it to “granitic pagmatites”.

14. In analytical methods: here you should state explicitly how many crystals were analysed in this study, and how many data points come from each crystal. This will make the info on Tables 1 and 2 clearer to the reader.

-In this paper, two beryl cystals from pegmatitic and four ones from hydrothermal mineralization of Xianglin area are taken as the kety research objects (Figure 5), and the location of samples is shown in Figure 3. Representative data of EPMA and LA-ICP-MS are listed on Tables 1 and 2, respectively.

15. Lines 315-316: numbers mentioned and phrase do not match.

-We have relaced “Fe” and “Mg” with “FeO” and “MgO”, respectively.

16. Line 330: implies

- We have revised the typo.

17. Line 340: elements

- We have revised the typo.

18. Lines 376-390: typos and some misused words here make this paragraph very confusing, please revise carefully.

- We have revised it.

“According to the crystallochemical formula of beryl, various cations are incorporated in the beryl structure, resulting in complex substitutions. As divalent cations, such as Fe²⁺ and Mg²⁺, substitute trivalent Al³⁺ in Y site (octahedral), leading to charge deficit, the long-radius monovalent cations and divalent cation Ca²⁺ enter the channel to balance the charge [59-64]. Since the Ca²⁺ and K⁺ contents of the two types of beryls from Xianglin area are negligible (Table 1), the occupying position of Ca²⁺ and K⁺  is not discussed in this paper. The atoms per formula unit of Be²⁺ in X site of Beryl-Ⅰ and Beryl-Ⅱ is 2.70 apfu and 2.89 apfu, respectively, showing obvious unsaturation. Li⁺ is the main substitute cation in X site, and the atoms per formula unit is 0.30 apfu and 0.11 apfu, indicating that the replacement degree of the X site ion of Beryl-Ⅰ is higher than that of Beryl-Ⅱ. The atoms per formula unit of Al³⁺ in Y site of Beryl-Ⅰ is 1.94 apfu and the substitution is 0.03 apfu, manifesting that the substitution degree of Y site of Beryl-Ⅰ is low. Whereas the atoms per formula unitof Al³⁺ is 1.76 apfu, and the substitution of Y site is 0.27 apfu, indicating that the substitution degree of Y site of Beryl-Ⅱ is relatively higher than that of Beryl-Ⅰ.”

19. Line 505: two-mica

- We have revised the typo.

20. Line 529: what is meant by dissolution of magmatic fluid?

- The geological characteristics, metallogenic chronology, stable isotopes and fluid inclusions of the Cuonadong Be-Sn-W polymetallic deposit show that the ore-forming materials and fluids of the deposit are derived from Cuonadong leucogranite [14-24]. Herein, we have revised it to be “With the continuous differentiation and crystallization of the leucogranitic magma, a large number of ore-forming materials such as Be, W and Sn are brought out. When the ore-bearing fluid is migrated to the marble layer with pressure releasing, extensive water-rock reaction occurs between ore-bearing fluid and marble layer [72], and then skarn be-W-Sn ore-body is formed(Fig.12).”

21. Line 598: Beryl occurrences in

- We have revised it to be “Beryl occurrences in …”