Encyclopedia
Pumice
Pumice is a very porous type of volcanic rock, rough to the touch and very light in weight, usually whitish or grey, but sometimes brown or red. This commodity category also includes crushed pumice (pumice gravel)
Source: "Explanations to the Commodity Nomenclature of the Foreign Economic Activity of the Russian Federation (Russian Customs Tariff)" (prepared by the Federal Customs Service of Russia) (Volume 1, Sections I - VI, Groups 1 - 29)