Metamorphic Rock

Gneiss (Metamorphic Rock)

Gneiss

Mica Schist

Mica Schist

Serpentine-bearing metamorphic rock (likely chromite/vesuvianite-bearing serpentinite)

Serpentinite, chiefly serpentine-group minerals [(Mg,Fe)₃Si₂O₅(OH)₄], with dark accessory minerals

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, with minor mica and iron-oxide impurities

Foliated metamorphic rock, likely gneiss or mica schist

Quartz–feldspar–mica metamorphic rock; exact identification is uncertain from the photograph

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly with quartz and feldspar

Garnet-bearing gneiss

Quartz–feldspar–mica gneiss with iron-rich garnet (commonly almandine)

Banded gneiss (likely biotite-bearing)

Gneiss; quartz–feldspar–mica assemblage, with possible iron-oxide staining

Pyrite-bearing metamorphic rock (probable schist or quartzite)

Quartz–mica schist with disseminated pyrite; approximate composition SiO₂ + phyllosilicates + FeS₂

Weathered mica-rich metamorphic rock

Probable biotite schist or mica schist

Iridescent schist or phyllite

Micaceous quartz-rich schist/phyllite, likely containing muscovite or chlorite

Serpentine-rich metamorphic rock (possibly serpentinite)

Serpentinite; chiefly antigorite, lizardite, or chrysotile with possible magnetite and carbonate minerals

Weathered foliated metamorphic rock, likely schist or phyllite

Micaceous quartz–feldspar schist/phyllite; exact identification requires microscopy or testing

Pyrite-bearing metamorphic rock (probable pyrite schist or sulfide ore)

Pyrite (FeS₂) in a foliated, quartz–mica-rich host rock; exact identification requires testing

Likely micaceous metamorphic rock fragment

Probable phyllite or mica schist; quartz–muscovite-rich assemblage

Pyrite-bearing metamorphic rock (probable pyrite schist)

Schist containing pyrite (FeS₂), with probable quartz and mica

Gneiss (Metamorphic Rock Pebble)

Foliated Metamorphic Rock (Quartz-Feldspar Gneiss / Granitic Gneiss)

Dark gray metamorphic rock fragment

Likely slate or fine-grained schist; mineral composition cannot be confirmed from the image

Blue-gray metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica assemblage; exact identification requires testing

Foliated mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly garnet-bearing

Honey calcite (likely rough cleavage fragment)

Calcite, calcium carbonate (CaCO₃)

Quartz-rich metamorphic rock, likely quartzite

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

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly migmatitic

Gray foliated metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and testing

Quartz-rich metamorphic rock, likely mica schist

Mica schist; chiefly quartz (SiO₂) with biotite/muscovite mica and possible feldspar

Quartz-rich metamorphic rock, possibly quartzite

Quartzite; primarily crystalline silicon dioxide (SiO₂), with minor feldspar, mica, or iron oxides

Quartz-rich metamorphic rock, likely quartzite

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

Quartz–feldspar–mica metamorphic rock, likely gneiss

Gneiss; composition commonly quartz (SiO₂), feldspars, biotite/hornblende, and minor accessory minerals

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests

Likely biotite-bearing metamorphic rock (schist or gneiss)

Mica schist/gneiss; chiefly quartz, feldspar, and biotite mica

Dark mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Quartz-veined Metamorphic Rock (Wishing Stone)

Quartz-veined Metamorphic/Igneous Host Rock with Quartz Veinlets

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly amphibolite-bearing

Weathered gray metamorphic rock, likely slate or phyllite

Foliated metapelite; composition commonly quartz, mica, and chlorite

Dark metamorphic rock, likely biotite schist or gneiss

Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing

Dark mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Quartz-rich metamorphic rock, likely garnet-mica schist or gneiss

Quartz–feldspar–mica metamorphic rock; probable biotite schist/gneiss

Quartz-bearing metamorphic rock, likely quartzite

Quartzite, predominantly SiO₂, with possible feldspar and mica impurities

Quartz-rich metamorphic rock, likely quartzite

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

Dark gray foliated metamorphic rock, likely slate or phyllite

Slate/phyllite; commonly quartz, muscovite/illite, chlorite, and graphite or carbonaceous matter

Banded metamorphic rock, likely gneiss or banded amphibolite

Undetermined foliated metamorphic rock; commonly quartz–feldspar–biotite gneiss or amphibolite

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly with mica or feldspar