Field book of common rocks and minerals

by Frederic Brewster Loomis

Sandstone gets a variety of names according to the cement.

Siliceous sandstone is cemented with silica and usually very hard.

Calcareous sandstone is cemented with lime and usually rather soft.

Ferruginous sandstone is cemented with one of the iron oxides.

Argillaceous sandstone is held together with clay impurities, and is usually both soft and of undesirable color.

According to their composition there is also a number of varieties.

Arkose is a sandstone composed of quartz and feldspar grains, usually derived from the disintegration of granite and not transported far.

Graywacke is a sandstone composed of quartz, feldspar, and some other mineral, like hornblende-augite, etc., also derived from the disintegration of granites and not transported far.

Grit is a term applied to a coarse sandstone, composed of angular quartz fragments, and used to a considerable extent for millstones.

Flagstone is a thin bedded sandstone, often with mica, which splits easily and uniformly along the bedding planes; so that it can be quarried in large slabs. It was widely used for sidewalks before the advent of concrete.