Subheading 261790 captures ores and concentrates of metals that do not have their own dedicated heading or subheading elsewhere in Chapter 26 — examples include bismuth, cobalt (when not covered by another provision), indium, and germanium ores. If a metal ore has a specific heading (e.g., copper, nickel, molybdenum), it must be classified there rather than here.

Antimony ore and concentrate classification and duty treatment should be verified at the specific tariff-line level, as trade-remedy measures can attach to particular lines and origins. Given antimony's designation as a critical mineral, importers should monitor CBP and USTR guidance for any new measures affecting this commodity.