Sandstones are composed of grains easily visible to the naked eye. They are generally lighter in color compared to finer-grained rocks and not as heavy. Pebbly sandstones and conglomerates have a sandstone matrix supporting distinctly larger rounded or irregular pebbles of other minerals or rocks, including coal.

Some gray or reddish-brown sandstones are especially hard and will effervesce when HCl is applied directly to the rock or to a powder created by scratching the core with a knife blade. Proceed to Carbonate Cements to further classify these rocks.

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