EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

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The EarthWord: Rock vs. Mineral

Definition:

• No, it’s not a replacement for Rock, Paper, Scissors. Instead, it’s a source of confusion for a lot of people. So we’ll try to clear this up a bit:

• Rocks are made of different kinds of minerals, or broken pieces of crystals, or broken pieces of rocks. Some rocks are made of the shells of once-living animals, or of compressed pieces of plants.

• Minerals are naturally occurring inorganic elements or compounds having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Minerals generally form crystals and have specific physical and chemical properties which can be used to identify them. Sometimes single minerals form rocks, as in quartz. Quartz is the most common form of crystalline silica and is the second most common mineral on the earth's surface.

• A good way to think about it is if a chocolate chip cookie was a rock, then the flour, sugar, butter, chocolate chips are the minerals that make up that rock!

Etymology:

• Rock comes from the Latin rocca, meaning “rock” or “stone.”

• Mineral comes from the Latin mineralis, meaning “something mined.”

Next EarthWord: It’s not a caffeinated ghost, but this EarthWord is nearly as trippy...

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