Where Did This Sand Come From?
ES1607  Interpreting the Clues

Here’s how to interpret the clues about the source of sand:

Shape
The shape of a grain can indicate how far it has traveled from its source. Generally, rounded grains have been transported longer distances than angular grains have.

Color/Composition
Color is usually an indicator of composition—the type of rock a grain came from. For example, if a sand grain is a volcanic mineral, a volcano is the likely source of the sand. Grains of obsidian (volcanic glass), olivine (an olive-colored volcanic mineral), and magnetite (a dark, magnetic mineral) all indicate a volcanic source of sand. Grains of quartz and feldspar indicate a granitic source.

Surface features
The presence of pits or holes on the surface of a grain suggests a volcanic source. Uniform ridges or holes sometimes reveal that a grain is part of a shell or a piece of coral, indicating a marine source for the sand.

  !   Click each image and interpret the clues about the source of each sample. Add the name of each sample and further details to your answers for question 1.

International Sand Collectors Society

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