This is a picture of a mineral taken through a microscope. You may find it hard to believe that this is a mineral, but it is! This piece of orthopyroxene was cut very thin, mounted on a slide, and viewed in a polarizing light microscope. The image contains features you wouldn’t be able to see by just looking at that piece of orthopyroxene with the unaided eye. A trained mineralogist can see that the orthopyroxene crystal formed first, then partly dissolved, and that augite crystals formed around the original crystals. Minerals are valuable resources for just about every aspect of our lives. When and where different minerals form are also important clues in telling the history of Earth.

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