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Type of rock and how it forms:
Sandstone is a sedimentary rock. Sand is deposited when currents in bodies of water slow down to the point that it can no longer carry sand grains. Once deposited, the grains (called clasts) are buried under layers of other sediment. Groundwater brings in a cement that precipitates in the spaces between the clasts. The cement ‘glues’ the grains together.
Minerals in sandstone and variations in appearance:
The sand in sandstone refers to the size of the clasts that make it up. The composition of the clasts depends on the source material at the time of deposition. Most sandstones (called arenites) are made up of quartz because it is resistant to breaking down (weathering). Other sandstones that have mineral or rock fragments that have not moved far from their source (and not had the time to weather into something else) can be pink or reddish in color because they are rich in feldspar (called an arkose). Another type of sandstone is a wacke that is grey in color because of rock fragments typically eroded off a mountain/volcano.
Arenites are consist mainly of quartz.
Where sandstone is found in NC:
There are several formations that have sandstone under the Coastal Plain of NC. Thick sections of older sandstone are found just to the west along the border with TN.
Uses:
Sandstone can be used as a building stone since it is soft and easy to cut and carve.
It is also used for decorative construction like fountains and sculptures.
Fun Facts:
The White House is made of a sandstone quarried in VA. It is white because of the sealant they put over the porous sandstone to keep moisture out.
The national parks of the desert southwest US are dominated by sandstone. Many of the sandstones were sediments blown in by the wind. Left behind are crossbeds recording the direction that the wind was blowing millions of years ago.
Sandstones can have fossils in them which preserve a record of life at the time the sand was deposited.
Read further at:
https://mineralseducationcoalition.org/minerals-database/sandstone/
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