The American Petroleum Institute (API) publishes specifications for drilling-grade barite covering minimum specific gravity, maximum soluble alkaline earth metals, and maximum residue on specific mesh sizes. Barytes that does not meet API 13A specifications may still be imported under heading 2511 for non-drilling uses such as paint, rubber, or radiation shielding, but drilling-fluid buyers typically require a certificate of conformance to the API standard.

Heading 2511 covers only the naturally occurring mineral forms — barytes as mined and at most processed by washing, drying, or grinding. Synthetic barium sulfate (blanc fixe), produced by chemical precipitation, is classified in the chapter covering inorganic chemicals. The distinction is origin: natural mineral deposit versus chemical manufacturing process. Importers should ensure that certificates of origin and product data sheets confirm the natural mineral source when classifying under 2511.