Exemption scope: imported ores qualify for customs-duty relief under the notification; concentrates excluded as manufactured products. The exemption under Serial Number 4 of Notification No. 4/2006 CE applies only to imported ores and not to imported concentrates. Chapter Note 4 to Chapter 26 distinguishes ores and concentrates as separate products, and concentrates are treated as manufactured products for central excise purposes; consequently, concentrates do not qualify for the additional duty exemption under Section 3 of the Customs Tariff Act even if classified under the same tariff heading as ores.