Clastic rock rich in lithics are called lithic sandstones. Siliciclastic sedimentary rocks are composed of mainly silicate particles derived by the weathering of older rocks and pyroclastic volcanism. While grain size, clast and cementing material (matrix) composition, and texture are important factors when regarding composition, siliciclastic sedimentary rocks are classified according to grain size into three major categories; conglomerates, sandstones, and mudrocks. The term clay is used to classify particles smaller than .0039 millimeters. However, term can also be used to refer to a family of sheet silicate minerals. Silt refers to particles that have a diameter between .062 and .0039 millimeters.
Eluvium the largest tin mines in the world. Weathering "supergene" enrichment of an apatite rich carbonatite in Ontario has produced a significant eluvial phosphate ore deposit. Eluvium In geology, eluvium or eluvial deposits are those geological deposits and soils that are derived by "in situ" weathering or weathering plus gravitational movement or accumulation. The process of removal of materials from geological or soil horizons is called eluviation or leaching. There is a difference in the usage of this term in geology and soil science. In soil science, eluviation is the transport of soil material from upper layers of soil to lower