DFS Analysis comparative to Other NI Stocks, page-9

Question to Jebster
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(I am not mining expert, sorry for my ignorance if my statement below makes no sense at all)
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My understanding is that Black Swan is an open pit mine while Silver Swan is underground mine which has been mined up to a depth of 1300 meters.
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New High Grade Resource are under Black Swan Open Pit mine and Drill Drive is in progress from Silver Swan underneath reaching below Black Swan. Once this Drill Drive is complete, POS will drill carry out Diamond Core Drill in various direction ?
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Also Some High Grades are below 1300 meter in Silver Swan also.
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My Question is : Is it economical to Dig 1300m or further ?