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The Rock Guide

An article about Rocks & Minerals

Here’s a quick guide on how to identify a rock.

Igneous Rocks

  • Intrusive Igneous Rocks

    • Large (visible) interlocking crystals

  • Extrusive Igneous Rocks

    • Porous (gas pockets)
    • Single color (light, medium, or dark)
    • Non-crystalline (glassy)

Metamorphic Rocks

  • Extremely dense
  • Banding (foliated)
  • Deformed
  • The presence of a quartz vein, pyrite, or garnet

Sedimentary Rocks

  • Fossils
  • Layers of sediment (visible sediment)
  • Pieces/fragments of other rocks cemented together

Please note: Some rock samples may be polished, which does not mean that they are glassy.