6815.91.00.11 - Containing by weight more than 70 percent magnesia, expressed as MgO, with carbon content ranging from trace amounts to less than 30 percent, and chemically bonded by resin or pitch

This HTS subcategory, 6815.91.00.11, specifically covers articles made from mineral substances, other than those elsewhere classified, which are characterized by a high magnesia content. The defining criteria include a weight percentage exceeding 70% magnesia (expressed as MgO) and a carbon content that is less than 30%, ranging from trace amounts up to that limit. Crucially, these articles are chemically bonded together using resin or pitch as the binding agent. This combination of high magnesia, specific carbon limits, and resin/pitch binding is essential for proper classification under this heading.

This classification is distinguished from its sibling category, 6815.91.00.71, which is designated for "Other" articles within the broader grouping of mineral articles containing magnesite, magnesia in the form of periclase, dolomite, or chromite. While both fall under the general umbrella of "Other articles: Containing magnesite, magnesia in the form of periclase, dolomite including in the form of dolime, or chromite," the .11 subcategory demands a precise composition of more than 70% magnesia (MgO) and less than 30% carbon, bonded by resin or pitch. The .71 subcategory serves as a residual category for other articles meeting the parent description but not meeting the specific compositional and binding requirements of .11.

As a leaf node in the HTS structure, there are no further subcategories branching from 6815.91.00.11. Therefore, classification within this heading relies entirely on accurately meeting the specified material composition and bonding agent criteria. Examples of goods likely to fall under this classification include specialized refractory bricks, linings, or shapes used in high-temperature industrial processes such as steelmaking or cement production, where the unique properties of magnesia and the bonding agent are critical for performance and durability.