Encyclopedia
Leads
4. Lidite - a very hard, rough, fine-textured and even finely-grained dark stone which is not affected by acids. Assay stones made of lidite (e.g., for testing precious metals) are included in customs commodity code 6815
Source: "Explanations to the Customs Tariff Nomenclature of the Russian Federation (HSN Russia)" (prepared by the Federal Customs Service of Russia) (volume 1, sections I - VI, groups 1 - 29)