Aleurite

ALEURITE (from the Greek word "aleuron", which means "flour" * EN: aleurite, silt; DE: Aleurit; FR: aleurite; ES: aleurita; RU: алеврит) is the loose fine clastic sedimentary rock, which is intermediate by its composition between the sands and clays; it consists primarily of the mineral grains (quartz, feldspar, mica, and others) of the size of 0.01-0.1 millimetres (according to the other sources, 0.005-0.05 millimetres).

Depending on the prevailing sizes of the grains, they distinguish the coarse aleurite (0.05-0.1 millimetres) and fine aleurite (0.01-0.05 millimetres) varieties, and in the latter one, depending on the peculiarities of the accumulation, also the tenuous aleurite (0.025-0.01 millimetres) one.

The term "aleurite" has been proposed by A.N.Zavaritskiy in 1930 for the rocks, which have lost the characteristic properties of the sands, but are not clays yet. The aleurite is used in the production of the cement and building ceramics.