SANDSTONE	A sedimentary rock consisting usually of quartz, cemented with silica, iron oxide or calcium carbonate, Sandstone is durable, has a very high crushing and tensile strength and a wide range of colours and textures. Varieties of sandstone are commonly designated by the kind and prominence of interstitial and bonding material, as siliceous sandstone (bonding material primarily silica), calcareous sandstone (calcium carbonate prominent as bonding material or as accessory grains or both), sandstone (clay minerals prominent as interstitial or bonding materials), or as thin laminac ferruginous sandstone (iron oxide or hydroxide minerals (hematite,, limonite, et al) as interstitial or as bonding materials in sufficient amount to impart appreciable colour of stone); brownstone (ferruginous sandstone of dark brown or reddish brown colour), arkose, arkosic sandstone, or feldspatic sandstone (a sandstone that contains an abundance of grains of feldspar), conglomerate (a sandstone composed in large part of rounded pebbles, also called puddingstone).
GROUP	Sedimentary
COMMON ROCK-FORMING MINERAL GROUP	Siliceous
COMPOSITION	The main minerals are quartz, feldspar and mica with a variety of accessory minerals. These minerals may be cemented by silica, calcite or iron oxides.
HARDNESS	Medium to Hard
MOHS' SCALE	4 - 7.5
POROSITY	0.5 - 35.0 %
ABSORPTION	0.2 - 9.0 %
WEATHERING CHARACTERISTICS	The types of cementing material and the presence of silt or clayey matter will determine how well the sandstone will weather in any given environment. Those cemented by silica and have a high quartz content are extremely resistant... Iron oxide cemented sandstones weather well in dry climates. They become harder and stronger, resisting weathering and deterioration. The calcite cemented sandstones are more easily weathered. When silt and clayey matter are present they form poor bonds and absorb water easily, this can be a cause of flaking and spalling. Also in colder climates the absorbed water freezes resulting in cracks and spalling. The surface of some sandstones may not weather uniformly, there may be a loss of material by flaking, spalling, etc. in some areas and not in others because sandstone is formed in layers. Some of these layers may be more resistant due to their composition and if the surface is cleft, different layers are exposed all resulting in a differential weathering process.
TENDENCIES	Absorbs oils and other liquids easily.
COLOURS	White to buff...Full range of earth tones to multi-coloured banded pastels
NOTATIONS	Due to the high absorption factor it is highly recommended for practical maintenance considerations and to minimize staining, that the stone be treated with a water/soil and or oil repellent.