2520 - Gypsum; anhydrite; plasters (consisting of calcined gypsum or calcium sulfate) whether or not colored, with or without small quantities of accelerators or retarders:

This HTS category, 2520, encompasses gypsum and anhydrite, as well as various plasters derived from calcined gypsum or calcium sulfate. These materials are primarily utilized in construction, but also find applications in agriculture and industry. The classification includes these substances whether they are in their raw, processed, or colored forms. Small quantities of accelerators or retarders, commonly added to modify setting times, do not preclude classification under this heading.

Distinct from its sibling categories within Chapter 25, which cover a broad range of minerals, earths, and stone, HTS 2520 is specifically focused on sulfur-based compounds. Unlike chapters dealing with live animals or manufactured goods, this section pertains to raw or semi-processed mineral substances. The defining characteristic for inclusion here is the chemical composition and the intended end-use as a plastering material or its primary constituent.

Subdivided into two distinct subcategories, 2520.10.00.00 covers the raw and calcined forms of gypsum and anhydrite, serving as the foundational material. The second subcategory, 2520.20.00.00, specifically addresses the prepared plasters, which are ready for application and may already contain additives. This division allows for finer distinctions based on the degree of processing and intended immediate use.