Analysis
HTS 2608.00.00 covers zinc ores and concentrates under heading 2608 (zinc ores and concentrates). US Customs collects import statistics for it under 5 ten-digit suffixes, reported in Cu kg.
Goods classified here enter the United States duty-free at the general (normal trade relations) rate, as do about 97% of the 39 tariff lines in chapter 26. Free here means free of the base duty only: origin-specific Chapter 99 duties such as Section 301 can still be owed.
It is the only US line under subheading 2608.00, so the six-digit code used by every Harmonized System country and the eight-digit US line describe the same goods; a foreign tariff or an exporter's invoice showing 2608.00 points straight here.
The ten-digit suffixes separate copper content, lead content, zinc content, silver content and gold content. The duty is the same across them; the suffix matters for statistics, licensing and some quotas, and an entry needs all ten digits.
Census statistics map these goods to NAICS 212230 (Copper, Nickel, Lead, and Zinc Mining), an industry of 61 US establishments employing 16,844 people. That is the industry code a US manufacturer of the same product would normally use.