Metamorphic Rock

Likely iron-rich metamorphic rock (possibly hematite-rich ironstone)

Unidentified ferruginous rock; exact mineralogy cannot be determined from the image

Likely basalt or mafic metamorphic rock

Basalt, predominantly plagioclase feldspar and pyroxene; possibly metamorphosed to amphibolite

Foliated metamorphic rock, likely mica schist

Mica schist, mainly quartz–feldspar–mica assemblage

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite (mostly microcrystalline quartz, SiO₂), possibly altered sandstone

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly with mica or iron-oxide impurities

Quartz vein in dark metamorphic rock

Likely quartz-rich vein cutting a biotite- or amphibole-rich metamorphic host; exact host rock cannot be confirmed from the image

Dark, foliated metamorphic rock (likely schist)

Probably mica schist; exact identification requires closer inspection or testing

Quartz-veined dark metamorphic rock

Likely quartz-bearing hornfels, amphibolite, or altered basalt; exact identification requires a fresh surface and tests

Coarse-grained metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (tentative; exact identification requires testing)

Biotite-bearing metamorphic rock, likely gneiss or schist

Mica-rich quartz–feldspar gneiss/schist; exact identification requires testing

Dark weathered metamorphic rock, likely schist or phyllite

Undetermined; probably mica-rich quartz–feldspar schist/phyllite

Iron-rich metamorphic rock (probable garnet-bearing schist or quartzite)

Garnet–quartz–mica schist/quartzite; composition likely quartz (SiO₂), iron oxides/hydroxides, mica, and possible almandine garnet

Foliated metamorphic rock, likely schist

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

Dark foliated metamorphic rock, likely slate or phyllite

Fine-grained metamorphosed mudstone; exact identification is uncertain from the photograph

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible mica or iron-oxide impurities

Banded metamorphic rock, likely gneiss

Foliated quartz–feldspar rock (gneiss; exact identification requires closer examination)

Banded metamorphic rock, likely gneiss or schist

Foliated quartz–feldspar–mica rock; exact identification requires a closer view or mineral testing

Dark, mica-rich metamorphic rock (probable schist or gneiss fragment)

Likely biotite–quartz–feldspar schist; exact identification requires testing

Foliated metamorphic rock, likely gneiss or schist

Biotite–quartz–feldspar gneiss/schist; exact identification requires a fresh surface and testing

Dark gray metamorphic rock, likely hornfels or fine-grained amphibolite

Hornfels/amphibolite; commonly quartz, feldspar, amphibole, biotite, and minor sulfides

Quartz-rich metamorphic rock, likely quartzite with mica

Quartzite; predominantly quartz (SiO₂) with probable muscovite/sericite mica and minor iron oxides

Foliated metamorphic rock (likely mica schist)

Mica schist, probably quartz–muscovite/biotite schist; exact identification requires close inspection

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

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

Weathered quartz-rich metamorphic rock (probable quartzite or gneiss fragment)

Quartzite–gneiss type specimen; chiefly SiO₂ (quartz) with feldspar, mica, and iron-oxide staining

Likely banded metamorphic rock, possibly schist or gneiss

Micaceous schist/gneiss; identification is limited from the photograph

Mica-rich metamorphic rock fragments

Biotite schist / mica schist (predominantly biotite, muscovite, and quartz)

Banded metamorphic rock, likely banded gneiss

Gneiss, probably biotite–quartz–feldspar gneiss

Banded metamorphic rock, likely gneiss

Banded quartzofeldspathic gneiss (probable paragneiss or orthogneiss)

Dark metamorphic rock, likely schist or gneiss

Mica schist/gneiss; commonly quartz + feldspar + biotite, with possible amphibole

Weathered gray metamorphic rock, likely schist or gneiss

Micaceous quartz-feldspar schist/gneiss; exact identification requires a fresh surface and testing

Foliated metamorphic rock, likely gneiss with amphibolite or chlorite-rich bands

Biotite–quartz–feldspar gneiss, locally mafic amphibolite; mineral composition is uncertain from the photograph

Banded metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification requires a fresh surface and mineral tests

Quartz-rich metamorphic rock, likely quartzite or quartz-veined schist

Quartz (SiO₂) with mica/chlorite-rich schistose matrix; possibly minor feldspar and sulfides

Likely quartz-bearing metamorphic rock

Probably quartzite or quartz-rich schist; mainly quartz (SiO₂), possibly mica and feldspar

Quartz-rich metamorphic rock, likely mica schist or quartzite

Quartz (SiO₂) with mica, feldspar, and possibly iron-oxide staining

Foliated mica-rich metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, muscovite/biotite, with possible amphibole or sulfide minerals

Weathered gray metamorphic rock, likely gneiss or schist

Probable quartz–feldspar–mica gneiss/schist; exact identification requires a fresh surface and tests

Weathered gray metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica assemblage; exact identification requires a fresh surface or testing

Gneiss

Foliated Metamorphic Rock (Gneiss)

Light-colored metamorphic rock, likely quartzite or marble

Quartzite (mostly SiO₂) or calcitic marble (mostly CaCO₃); image resolution prevents confident distinction

Weathered iron-rich metamorphic rock, likely schist or quartzite

Provisional identification: ferruginous quartzite or mica schist; composition likely quartz (SiO₂), iron oxides/hydroxides, and mica or clay minerals

Banded metamorphic rock, likely gneiss or amphibolite

Composition uncertain; probable quartz–feldspar–amphibole assemblage