Metamorphic Rock

Foliated mica-rich metamorphic rock, likely schist

Mica schist; predominantly quartz, feldspar, and biotite/muscovite mica

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline quartz (SiO₂), possibly with feldspar and mica impurities

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, with minor feldspar and iron-oxide staining

Mica-rich metamorphic rock (likely schist)

Muscovite–biotite schist; predominantly phyllosilicate mica minerals in a quartz/feldspar matrix

Weathered quartz-rich metamorphic rock, probably quartzite

Quartzite; predominantly microcrystalline SiO₂, possibly with feldspar and iron-oxide staining

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, with minor feldspar or mica

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible mica and iron-oxide inclusions

Mica-bearing metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly with quartz and feldspar

Chlorite-rich metamorphic rock, likely greenschist

Greenschist; commonly composed of chlorite, actinolite, epidote, albite, and quartz

Quartz vein in foliated metamorphic rock

Milky quartz (SiO₂) in likely schist or gneiss

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible feldspar, mica, and iron-oxide staining

Banded metamorphic rock, likely mica schist

Mica schist, chiefly quartz, muscovite/biotite, and feldspar

Weathered iron-rich metamorphic rock

Likely iron-stained quartzite or metasedimentary rock; exact identification requires testing

Quartz-rich metamorphic rock (probable quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with mica and iron-oxide impurities

Likely biotite-rich metamorphic rock (mica schist or amphibolite)

Mica schist/amphibolite; chiefly biotite mica ± hornblende, plagioclase, quartz

Foliated metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica gneiss/schist; exact identification requires petrographic examination

Dark green-black metamorphic rock, likely serpentinite

Serpentinite; chiefly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile, with magnetite and minor chromite

Dark veined metamorphic rock, likely serpentinite

Serpentinite; predominantly serpentine-group minerals, possibly with magnesite or calcite veins

Mica-rich metamorphic rock, likely schist

Quartz–mica schist; commonly quartz with muscovite and/or biotite mica

Blue-gray metamorphic rock fragment

Likely slate or phyllite; exact identification is uncertain from the photograph

Foliated metamorphic rock, likely slate or phyllite

Slate–phyllite; composition commonly quartz, mica, and chlorite

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-mica schist; predominantly SiO₂ quartz with possible feldspar and mica

Graphite-rich metamorphic rock (probable graphite schist)

Graphite schist; predominantly graphite (C) with quartz and mica

Weathered mica-rich metamorphic rock, likely schist

Mica schist, probably muscovite–biotite schist with quartz and feldspar

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with feldspar and mica impurities

Quartz-rich metamorphic rock, likely quartzite

Quartzite, predominantly crystalline SiO₂, with probable iron-oxide staining and minor feldspar/mica

Mica-rich metamorphic rock, probably phyllite or schist

Quartz–mica phyllite/schist, dominated by muscovite or biotite mica and quartz

Weathered metamorphic rock, likely slate or phyllite

Fine-grained foliated rock, probably quartz–mica-rich phyllite (exact identification requires testing)

Iron-rich metamorphic rock, likely banded iron formation fragment

Banded iron formation (BIF), chiefly hematite–magnetite with chert; exact identification requires testing

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), possibly with feldspar, mica, and iron-oxide staining

Likely quartz-rich metamorphic rock (quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with mica or feldspar

Quartz-bearing metamorphic rock, likely mica schist or gneiss fragment

Muscovite–biotite schist/gneiss with quartz and feldspar

Quartz-rich metamorphic rock, possibly mica schist

Muscovite–biotite schist with quartz; exact identification requires testing

Micaceous iron-rich metamorphic rock (probable schist)

Biotite–muscovite quartz schist, possibly containing hematite or sulfide minerals

Fine-grained dark metamorphic rock, likely slate or phyllite

Slate/phyllite; chiefly quartz, mica, and chlorite

Iron-rich metamorphic rock (probable limonite/goethite-bearing schist)

Quartz–mica schist with iron oxyhydroxides, chiefly goethite (FeO(OH)) and limonite (amorphous hydrated iron oxides)

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly SiO₂ with iron-oxide staining and minor feldspar/mica possible

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline quartz (SiO₂), possibly with feldspar or mica

Mixed metamorphic rock fragments, likely garnet-bearing schist and quartzite

Quartz–feldspar–mica schist/quartzite; red grains may be almandine garnet

Weathered quartz-rich metamorphic rock

Probable quartzite or quartz-rich gneiss; predominantly SiO₂ with feldspar and minor mica/iron oxides

Weathered quartz-rich metamorphic rock, likely quartzite or gneiss

Quartzite/gneiss; chiefly quartz (SiO₂) with feldspar and mica/iron oxides