https://www.usgs.gov/publications/geologic-criteria-assessment-sedimentary-exhalative-sedex-zn-pb-ag-deposits
Geologic Criteria for the Assessment of Sedimentary Exhalative (Sedex) Zn-Pb-Ag Deposits | U.S....
Sedex deposits account for more than 50 percent of the world's zinc and lead reserves and furnish more than 25 percent of the world's production of these two...