Metamorphic Rock

Rounded greenish metamorphic rock, likely serpentinite

Serpentinite, composed mainly of serpentine-group minerals (antigorite, lizardite, or chrysotile)

Serpentine-rich metamorphic rock

Serpentinite; chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄, possibly with talc, chlorite, magnetite, or carbonate

Weathered greenish metamorphic rock, possibly serpentinite

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, or chrysotile)

Weathered foliated metamorphic rock, likely schist or phyllite

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

Weathered micaceous metamorphic rock, likely schist or phyllite

Quartz–mica schist/phyllite; commonly quartz, muscovite/biotite, and feldspar

Serpentine-rich metamorphic rock

Serpentinite, primarily serpentine-group minerals [Mg₃Si₂O₅(OH)₄], possibly with magnetite and/or chromite

Kyanite-bearing metamorphic rock

Blue kyanite (Al₂SiO₅), likely in mica- and garnet-rich schist

Rhodonite-bearing metamorphic rock

Rhodonite (MnSiO₃) in manganese-rich schist/gneiss, possibly with quartz and amphibole

Rhodonite-bearing metamorphic rock (likely rhodonite schist or altered manganese-rich rock)

Rhodonite (MnSiO₃) with probable quartz, feldspar, and/or manganese silicates

Serpentine-rich metamorphic rock

Serpentinite; chiefly antigorite/lizardite/chrysotile, commonly with magnetite and carbonate

Weathered layered metamorphic rock, likely schist or phyllite

Micaceous quartz–feldspar schist/phyllite; exact identification requires a fresh surface and testing

Serpentine-rich metamorphic rock

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible chlorite, magnetite, and altered olivine/pyroxene

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

Gneiss (Metamorphic Rock Pebble)

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

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

Quartz-bearing metamorphic rock, likely quartzite

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

Mica schist

Muscovite–biotite schist, commonly with quartz and feldspar

Weathered granitic or metamorphic rock fragment

Indeterminate; likely quartz–feldspar–mica-bearing granitoid or gneiss

Quartz-rich metamorphic rock, likely quartzite

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

Small banded metamorphic rock fragment

Indeterminate foliated metamorphic rock; possibly mica schist or gneiss

Weathered quartz-rich metamorphic rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining and dark inclusions

Polished granite or gneiss stone

Granite, chiefly quartz, feldspar, and dark mica/amphibole; exact identification is uncertain from the photograph

Likely slate or fine-grained metamorphic rock

Slate; predominantly microcrystalline quartz, mica, and clay minerals

Dark gray fine-grained stone, likely basalt

Basalt; chiefly plagioclase feldspar and pyroxene, commonly with minor olivine and iron oxides

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

Metamorphic rock outcrop, likely schist or gneiss

Foliated metamorphic rock; exact mineral assemblage cannot be determined from the image

Likely gray-green metamorphic rock fragment

Unidentified fine-grained metamorphic rock; exact identification is not possible from this small image

Quartz-bearing reddish metamorphic rock, possibly ferruginous quartzite or jasper vein

Quartz (SiO₂) with iron oxides; likely quartzite or iron-rich jasper

Weathered mica-rich metamorphic rock

Probable biotite schist or mica schist

Dark green metamorphic rock, likely serpentinite

Serpentinite, chiefly serpentine-group minerals (antigorite/lizardite/chrysotile), commonly with magnetite and chromite

Dark foliated metamorphic rock, likely amphibolite

Amphibolite, typically composed mainly of hornblende and plagioclase feldspar

Rounded gray river pebble, likely fine-grained basalt or andesite

Basaltic-andesitic volcanic rock; commonly plagioclase feldspar, pyroxene, and minor iron oxides

Quartz-veined metamorphic rock, likely schist or phyllite

Quartz-bearing mica schist/phyllite; exact identification requires closer examination

Mica-rich metamorphic rock, likely biotite schist

Biotite–quartz schist; probable composition of quartz, biotite, feldspar, and minor sulfide or iron-oxide minerals

Mica-rich metamorphic rock, likely biotite schist

Biotite schist; chiefly quartz, feldspar, and biotite mica

Gray metamorphic rock, likely gneiss or schist

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

Foliated mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly garnet-bearing

Banded metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica gneiss/schist; exact identification requires thin-section or tests