2528.00.00.50 - Other

This HTS category, "Other," specifically covers natural borates and their concentrates that do not fall under the more precisely defined categories of natural sodium borates or natural calcium borates. This classification is intended for borate products that are not readily categorized as solely sodium or calcium based. It encompasses calcined forms of these other natural borates, as well as natural boric acid, provided that the boric acid content, calculated on a dry weight basis, does not exceed 85%. The key differentiating factor for inclusion here is the absence of a predominant natural sodium or calcium borate composition, or the boric acid content threshold being met.

Unlike its sibling categories, which focus on specific mineral compositions (natural sodium borates and natural calcium borates), this "Other" designation serves as a residual category for natural borates that do not fit those specific definitions. For example, if a natural borate concentrate contains a mixture of mineral constituents with no single element being clearly predominant as sodium or calcium, or if it is a natural boric acid that is less concentrated than the threshold for the primary boric acid classification, it would likely be classified here. The critical consideration is the chemical composition and purity, particularly concerning the percentage of boric acid for boric acid entries.

As this is a leaf node within the HTS structure, there are no further subdivisions. Therefore, the focus for classification under 2528.00.00.50 is on ensuring that the natural borate or boric acid product in question does not meet the criteria for the more specific sibling categories. This requires careful analysis of the product's mineralogical and chemical makeup to confirm it is neither primarily a natural sodium borate nor a natural calcium borate, and that any natural boric acid falls within the specified concentration range.