Sandstone

A medium-grained clastic sedimentary rock composed of fragments of sand size (0.1-2mm diameter) set in a fine-grained matrix (silt or clay) and more or less firmly united by a cementing material (commonly silica, iron oxide, or calcium carbonate); the consolidated equivalent of sand. The sand particles usually consist mostly of quartz, and the term sandstone, when used without qualification, indicates a rock containing more than about 80% quartz. The rock is usually a pale sandy colour but varies greatly in color. It may be deposited by water or wind and may contain abundant primary sedimentary features (fine and coarse bands, ripple marks, fossils, etc.). Sandstones are classified mostly according to the composition of the clastic particles and matrix, and also sometimes by mineralogic or textural maturity, fluidity index, diastrophism, and primary structures.

Also used more broadly for any sandstone or sand-grade clastic-sedimentary-rock composed of sand-sized fragments irrespective of composition; e.g., sandstone, graywacke, arkose, and calcarenite. Note the majority of sandstone can be classed as silicate-sandstone.

Ref: AGI