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Identify metamorphic rock in the field

Short answer

Metamorphic rocks show foliation (slaty cleavage, schistosity, banding), sugary interlocking texture in non-foliated types, and metamorphic minerals (garnet, kyanite). They lack fossils, display deformation structures, and are hard and dense, often found near mountain belts.

How do you identify a metamorphic rock in the field?

A metamorphic rock can be recognised in the field by these features.

  1. Foliation: parallel arrangement of minerals, banding or flaky layers (slate, phyllite, schist, gneiss).
  2. Slaty cleavage or schistosity: splits into thin sheets, with silky or shiny mica surface.
  3. Crystalline, interlocking, "sugary" texture in non-foliated types (marble, quartzite).
  4. Metamorphic minerals present: garnet, kyanite, staurolite, chlorite, talc, epidote.
  5. Deformed or distorted structures such as folds, stretched pebbles, and lenticular bands.
  6. No fossils (or highly distorted ones).
  7. Hard and dense; the rock is often found near mountain belts, fault zones or intrusions.

✓ Answer checked by Claude Opus 5.5 (high effort)

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