Everyday Uses of Rocks and Minerals - Shelf 3

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Granite and marble counter tops are made from stone. Granite forms when magma cools within the earth and never erupts from a volcano. The slower it cools, the larger the mineral grains that form. Marble is formed from limestone that is cooked by heat and pressure within the earth.

Salt is a mineral formed from the elements sodium and chlorine, each of which is deadly on its own. Together they make an essential nutrient. Most salt is formed by the evaporation of sea water. Sea salt is made from the evaporation of seawater today, while regular salt is mined from ancient deposits created when seawater evaporated during warm intervals in the past.

Glass is formed by melting quartz, the primary mineral found in sand. Sand is all that's left over after granite is ground down by streams, rivers, and the action of ocean waves. As the mineral quartz, silica is very hard, which is why it stays intact in sand, even as all of the other minerals from granite are destroyed. When it's melted into glass, it loses its mineral strength, but becomes clearer and can be formed while it's molten.