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HSChapter 25
U.S. imports of mullite (HS 250860) totaled $950K in July 2026, traded with 8 countries.
Importers of Mullite paid $16K in duties in July 2026 — an effective duty rate of 10% on $156K in dutiable value, based on actual customs collections rather than the published tariff schedule.
Last updated: July 2026 dataMullite is a high-performance aluminosilicate mineral prized in the refractory and advanced ceramics industries for its exceptional thermal stability, low thermal expansion, and resistance to creep at elevated temperatures. It serves as a critical raw material for kiln furniture, furnace linings, and technical ceramic components used in steel, glass, and aerospace manufacturing. The sole US tariff line for this mineral is 2508600000, making classification straightforward, though distinguishing natural from synthetic mullite can affect duty treatment and sourcing decisions.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
31 shipments/mo
Mullite is classified specifically under HTS 2508600000 as a naturally occurring or synthetically produced aluminosilicate with a defined crystal structure. Customs may request mineralogical analysis or a certificate of composition to confirm the product meets the mullite specification rather than being classified as a generic clay or other mineral.
The primary demand comes from refractory manufacturers supplying the steel, glass, and ceramics industries, where mullite's high melting point and low thermal expansion make it essential for kiln furniture, furnace linings, and high-temperature structural components.
Subheading 2 of 6 in heading 2508
Subheading 250860 · $950K of $3.1M
ImportsExports
Imports
$950KYoY · Pro
Exports
$866KYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.
Imports · July 2026
origin
Canada and Germany together supply 92% of it.
customs district
destination
entry
rate provision · imports
83.6% enters free of duty; the effective duty rate is 1.64%.
HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share | Duty Collected |
|---|---|---|---|---|---|
| 2508600000 | Mullite | $950K | 1.64% | 16.42% | $16K |
HS10 export codes under this HS6 parent, each with its own page. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 2508600000 | Mullite | $866K |
Import lines come from the U.S. Harmonized Tariff Schedule and export lines from Schedule B. The two are numbered by different agencies, so the same 10-digit code can appear in both tables describing a different product.
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