Review Reports - Estimation Accuracy and Classification of Polymetallic Nodule Resources Based on Classical Sampling Supported by Seafloor Photography (Pacific Ocean, Clarion-Clipperton Fracture Zone, IOM Area)

Round 1

Reviewer 1 Report

See attached PDF.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thank you very much for your time and reviewing the manuscript titled: “Estimation accuracy and classification of polymetallic nodule resources based on classical sampling supported by seafloor photography (Pacific Ocean, Clarion-Clipperton Fracture Zone, IOM area)”.

In the attachment we send a modified version of the manuscript with an indication where the text have been completed.

Best regards

Jacek Mucha and Monika Wasilewska-Błaszczyk

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors and editor

This is a very interesting paper and represents an important contribution to establish the guidelines about the resource estimation and classification of polymetallic nodules offshore. It is well organized and illustrated and very well written.

The authors discuss the methodologies applied to estimate the accuracy and to classify the mineral resources and suggest a new approach, using seafloor photography. However, a key component of any resource classification is grade continuity. I agree that the abundance of polymetallic nodules is a very good proxy to assess geological continuity but how about the grade continuity?

The authors completely ignored this aspect in their study and also in their proposed methodology to classify offshore polymetallic nodules. Variations in metal content will obviously have an economic impact on the project and must be considered in the resource classification.

It may be the case that the metal content doesn’t vary significantly. If that is true, it should be explained in the introduction. Otherwise, I suggest the authors discuss why they are not considering grade continuity into their proposed methodology.

I would recommend publishing the manuscript only after this explanation is provided in the body of the text, either in the introduction or in the discussion section (or both).

Regards