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Metamorphic Rock Identification Chart

Metamorphic rocks are changed in the solid state by heat, pressure, deformation, and reactive fluids; if a rock fully melts, the resulting rock is igneous rather than metamorphic. Practical hand-sample classification begins with fabric and then mineral composition. Very fine planar slaty cleavage supports slate. Fine wavy foliation with a silky mica sheen supports phyllite. Visible aligned platy minerals define schistose fabric and support schist, while coarse light-and-dark compositional banding supports gneiss. These boundaries can be gradational and a complete schist name commonly includes diagnostic minerals. Non-foliated metamorphic rocks form interlocking mosaics and are often named by composition: quartz-rich material supports quartzite, carbonate-rich material supports marble, amphibole-rich mafic material supports amphibolite, talc-rich material supports soapstone, and serpentine-rich material supports serpentinite. Dense fine-grained rock beside an intrusion can support hornfels, and intense planar grain-size reduction can support mylonite-series rock. Sedimentary bedding, igneous flow banding, veins, weathering, and slickensides can imitate metamorphic fabric. GeoMiner's private selector sends only bounded fabric and composition groups—never a specimen name, free text, photo, location, exact colour, mineral percentages, index-mineral list, measurements, or interpreted grade. Do not cut, grind, or abrade serpentinite or fibrous material. A field name does not establish protolith, metamorphic grade, or pressure–temperature history; those may require mineral assemblages, petrography, chemistry, and structural context.

  • Quick ID for foliated rocks — Carry a broad fabric into the account-free property key.
  • Slate vs phyllite — Compare planar slaty cleavage with fine wavy foliation and a continuous silky sheen.
  • Phyllite vs schist — Use matrix grain visibility and aligned mica to test the gradational boundary.
  • Schist vs gneiss — Separate schistosity from persistent light-dark compositional banding.
  • Shale vs slate — Separate bedding-parallel fissility from metamorphic slaty cleavage.
  • Gneiss vs granite — Compare mineral segregation and foliation with massive intrusive texture.
  • Marble vs limestone — Compare a recrystallized mosaic with fossils, pores, grains, and bedding.
  • Rock reference library — Verify candidates against the source-backed rock catalogue.

Verification resources

Cross-check terminology, classification, methods, and safety with these authoritative external resources.

  • undefined. Solid-state metamorphism, foliated and non-foliated textures, and common rock examples.
  • undefined. Foliation from aligned minerals and examples including slate, schist, gneiss, marble, quartzite, hornfels, and soapstone.
  • undefined. A texture, grain-size, composition, and metamorphic-setting identification scheme.
  • undefined. Fabric-based and composition-based metamorphic rock classes including slate, schist, gneiss, hornfels, marble, quartzite, and serpentinite.
  • undefined. Classification by texture and composition, including the slate–phyllite–schist–gneiss sequence and non-foliated rocks.
  • undefined. Foliation-first naming, composition-based marble and quartzite, protolith limits, amphibolite, and index-mineral context.

Read GeoMiner's editorial methodology.

Common questions

How do I identify a metamorphic rock?
Look for foliation, cleavage, aligned minerals, compositional banding, strong shearing, or a non-foliated recrystallized mosaic, then combine fabric with mineral composition and field context.
What separates slate, phyllite, schist, and gneiss?
Slate is very fine with planar cleavage; phyllite is fine with a silky sheen; schist has visible aligned platy minerals; gneiss has coarse compositional banding.
What is the difference between foliated and non-foliated metamorphic rocks?
Foliated rocks show a planar or layered mineral fabric. Non-foliated rocks lack a pervasive planar fabric and commonly form an interlocking mosaic.
How can I tell quartzite from marble?
Quartzite is quartz-rich and hard; marble is carbonate-rich and softer. Controlled tests and field context are needed because sandstone and limestone are look-alikes.
Does foliation tell me metamorphic grade?
Not by itself. Mineral assemblage, protolith composition, texture, deformation, and pressure–temperature history all matter.

JavaScript is loading the interactive GeoMiner experience. The identification tools provide educational candidates, not laboratory confirmation.