No. Antimony trioxide and other antimony oxides are inorganic chemical compounds classified in Chapter 28, not under heading 8110. Heading 8110 covers the metal antimony and articles made from it. Importers of antimony trioxide for flame-retardant applications should look to the relevant Chapter 28 subheading.

The US critical-mineral designation reflects concern about supply concentration: a large share of global antimony production and refining has historically been concentrated in a small number of countries. Importers relying on a single-country supply chain should assess exposure to export restrictions or policy changes, and may wish to qualify alternative sources or maintain strategic inventory buffers.