Analysis
HTS 2502.00.00 covers unroasted iron pyrites under heading 2502 (unroasted iron pyrites).
There is no general-rate duty on this line, which puts it with roughly 91% of the 78 tariff lines in chapter 25 that are also free. 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 2502.00, 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 2502.00 points straight here.
Census statistics map these goods to NAICS 21239 (Other Nonmetallic Mineral Mining and Quarrying), an industry of 236 US establishments employing 10,238 people, the industry a domestic producer of these goods reports under.
The general rate of Free has not changed in any edition of the schedule since Jan 2023.