Andalusite, kyanite and sillimanite
Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: > Andalusite, kyanite and sillimanite
Duty Rate (from China)
Except for products described in headings 9903.03.02–9903.03.11, articles the product of any country, as provided for in subdivision (aa) of U.S. note 2 to this subchapter
Except as provided in headings 9903.88.13, 9903.88.18, 9903.88.33, 9903.88.34, 9903.88.35, 9903.88.36, 9903.88.37, 9903.88.38, 9903.88.40, 9903.88.41, 9903.88.43, 9903.88.45, 9903.88.46, 9903.88.48, 9903.88.56, 9903.88.64, 9903.88.66, 9903.88.67, 9903.88.68, or 9903.88.69, articles the product of China, as provided for in U.S. note 20(e) to this subchapter and as provided for in the subheadings enumerated in U.S. note 20(f)
Products classified under HTS 2508.50.00.00
Calcined Kyanite Powder
Calcined kyanite is a high-alumina aluminosilicate mineral processed by heating to stabilize its crystal structure, preventing volume expansion during ceramic firing. It is classified under HTS 2508.50.00.00 as calcined kyanite, a form of sillimanite group mineral used primarily in refractory and ceramic applications.
Raw Andalusite Ore
Raw andalusite ore consists of natural andalusite crystals extracted from deposits, typically containing 55-60% alumina. Classified under HTS 2508.50.00.00 as uncalcined andalusite, it serves as a raw material for refractory bricks and high-temperature ceramics.
Sillimanite Grain for Refractories
Sillimanite grains are crushed and sized particles of sillimanite mineral (Al2SiO5) used in refractory castables and ramming mixes. This product falls under HTS 2508.50.00.00 as unprocessed sillimanite, valued for its high melting point above 1600°C.
Calcined Andalusite 55% Al2O3
Calcined andalusite with 55% alumina content is heat-treated to convert partially to mullite, improving thermal shock resistance. HTS 2508.50.00.00 covers this calcined form before further processing into finished refractories.
Kyanite Flour -325 Mesh
Ultra-fine kyanite flour (-325 mesh, <44 microns) used as filler in porcelain insulators and spark plugs. Classified under HTS 2508.50.00.00 as ground kyanite, not chemically modified.
South African Andalusite Lumps
Andalusite lumps from South African Namaqualand deposits, sized 10-100mm, containing 58% Al2O3. HTS 2508.50.00.00 applies to this natural uncalcined mineral export product used globally in steel ladle refractories.
Mullite-Forming Kyanite Concentrate
Beneficiated kyanite concentrate selected for optimal mullite formation during firing, 99%+ purity. Falls under HTS 2508.50.00.00 as processed but uncalcined kyanite per Chapter 25 definitions.
Indian Sillimanite Sand
Beach sand deposit sillimanite from Indian coastal mines, washed and dried to -100+200 mesh. HTS 2508.50.00.00 covers this naturally concentrated sillimanite used in investment casting shells.