How Do I Know This Rock Is Sandstone?

Look for a sandy composition. Upon examination of a suspected piece of sandstone, you should be able to see a small grainy texture. Sometimes, but not always, the texture is luminous because of a majority of quartz particles being present. Despite its sandy nature, sandstone is generally hard to break into pieces; if it is easily breakable, it might be another composite stone with similar characteristics. A cement formed from silica or calcium carbonate is usually around the particles.

Determine if the color is consistent with sandstone samples. Most sandstone is tan or yellow, the typical colors that are present when there are many feldspar particles present. Sometimes, the sandstone will appear translucent, but more often, it is opaque with some dull luster from the quartz. Darker sandstone, like the red-hued version, is rare.

Look for layering characteristics that are common to sandstone. Most sandstone has layering that is consistent with it being formed in desert ecosystem; the pattern most often looks like a sand dune. If the layers are more irregular, it is a sign that the rock was exposed to water during formation. Sandstone that has been exposed to water for a long period of time usually disintegrates.

Research the scientific properties of sandstone. All stones are characterized by the Mohr hardness scale, which can be learned by touch in a relatively short amount of time. Talk to local geologic museum or the geology department of a local university for a quick lesson. Sandstone has a density that ranges from 2 to 2.65, relative to the density of water, and scores a 7 on the Mohr hardness scale.