Arenaceous

[Lat. arenaceus, from arena, sand.] Sandy; having the properties of sand. A. Rocks. ( Geol .) The name given to rocks composed entirely, or to a large extent, of grains of silex. Beds of loose sand occur extensively in the more recent deposits. The grains, either of quartz or flint, are generally water-worn and rounded. In older deposits, the grains of sand are bound together by silicious, calcareous, argillaceous, or ferruginous cements. It is seldom that a rock is composed of quartzose materials alone; grains or particles of other mineral substances are frequently mingled with the grains of quartz. Silvery flakes of mica are seldom absent; and they often occur in layers parallel to the planes of stratification, causing the rock to split into thin slabs, and exposing a glittering surface. These are called micaceous sandstones. When grains of feldspar occur, it is a feldspathic sandstone. Often large quantities of calcareous matter, either as cement or as distinct grains, occur; and these are called calcareous sandstones. The presence of lime can always be detected by the effervescence which takes place on the application of muriatic or other acid. When the sandstone is coarse-grained, it is usually called gril . It becomes conglomerate , or pudding - stone , if the grains are large enough to be called pebbles; or brec cia , if the fragments are sharp and angular.