2511 - Natural barium sulfate (barytes); natural barium carbonate (witherite), whether or not calcined, other than barium oxide of heading 2816:

HTS heading 2511 encompasses natural barium sulfate, commonly known as barytes, and natural barium carbonate, also referred to as witherite. Barytes, a sulfate mineral of barium, is typically found in white or off-white dense crystals or masses. Witherite, a carbonate mineral of barium, is also a naturally occurring substance that may be subjected to calcination (heating to remove impurities or change its form). Both are valued for their unique physical properties, such as high density and low solubility, which lend them to various industrial applications.

This heading is distinct from other headings within Section V, particularly those concerning crude minerals. For instance, it does not include other naturally occurring mineral earths or stones not specifically enumerated, nor does it cover metallic ores or refined metallic compounds. The focus here is on specific barium-containing minerals in their natural or calcined carbonate form, excluding processed barium compounds like barium oxide, which fall under Chapter 28.

Within heading 2511, further distinctions are made based on the specific barium mineral. Subheading 2511.10 covers natural barium sulfate (barytes), differentiating it from the barium carbonate. Subheading 2511.20.00.00 then addresses natural barium carbonate (witherite). This subdivision allows for precise classification based on the chemical composition of the barium mineral, ensuring accurate tariff application for trade purposes.