Sandstone is a sedimentary layer of stone. It can sometimes contain an aquifer, and can also be found along the ocean shore.
It also is the name for the eighth month of the Dwarven calendar, covering mid-Autumn.
 In Real Life
Sandstone is a sedimentary stone composed of broken pieces of minerals, usually quartz or potassium feldspar, cemented together with either the minerals hematite (Fe2O3), calcite (CaCO3), or silica (SiO2), or through sheer pressure compacting the grains together. When the individual grains are larger than 2 millimeters, the stone is called a conglomerate if the grains are rounded, or a breccia (not present in Dwarf Fortress) if the grains have sharp points or angles. If the individual grains are smaller than 1/16th of a millimeter, the stone is called a siltstone. When sandstone is exposed to high heat, such as through magma coming into contact with the stone, the grains melt and are recrystallized, forming the stone quartzite. It is found in numerous colors, most common being yellow, red, gray, white, tan, and brown.
Natural sandstone corridor
Door frame made from sandstone
A 17.000 year old sandstone oil lamp, made for use with deer fat
Significant melting/boiling point contributions by:
Jan-Willem "Great Cthulhu" van den Broek
Uristocrat: Density values from the research thread: