(a) Terrigenous components: Derived from erosion of areas outside the depositional basin. Brought to the basin as solids. Examples are quartz and feldspar sand, heavy minerals, clay minerals, and chert and limestone clasts. (b) Allochemical components Greek: "allo" meaning different from normal. Precipitated directly from solution within the depositional basin. Termed"allo" because they have been moved as solids within the basin. Examples: broken or intact shells, oolites, calcareous pellets, or fragments of carbonate sediments. (c) orthochemical components Greek: "ortho" meaning true. Termed"ortho" because they are produced chemically within the basin. Examples: microcrystalline calcite or dolomite ooze, some evaporites, and cements in sandstones.