Metamorphic Rock

Quartz-rich metamorphic rock, likely quartzite with mica

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

Banded metamorphic rock, likely banded gneiss

Gneiss, probably biotite–quartz–feldspar gneiss

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

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

Quartz-rich metamorphic rock, likely quartzite or vein quartz

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

Weathered mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar, with minor biotite, quartz, or garnet

Weathered quartz-rich metamorphic rock (probable quartzite)

Quartzite; predominantly crystalline SiO₂, possibly iron-oxide stained

Banded metamorphic rock, likely mica schist

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

Weathered quartz-rich metamorphic rock (probable quartzite)

Quartzite, primarily microcrystalline quartz (SiO₂), with possible iron-oxide staining and minor mica/feldspar

Quartz-rich metamorphic rock (likely mica schist or gneiss)

Quartz–feldspar–mica assemblage; probable biotite schist/gneiss

Weathered quartz-rich metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica gneiss/schist (tentative; image resolution limits certainty)

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist; principally muscovite mica, biotite, quartz, and feldspar

Weathered, quartz-rich metamorphic rock (likely schist or gneiss)

Quartz–feldspar–mica schist/gneiss, with surface lichens and iron-oxide staining

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite (mostly microcrystalline SiO₂), possibly iron-stained mica-bearing quartzite

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂) with iron-oxide staining and minor feldspar/mica

Pyrite-bearing metamorphic rock (likely schist or gneiss)

Pyrite (FeS₂) in a quartz–mica-rich host rock

Banded quartz-rich metamorphic rock (likely gneiss or quartzite)

Banded quartz–feldspar–mica rock; exact identification requires testing

Foliated metamorphic rock, likely marble or calc-schist

Calcite-rich marble/calc-schist; predominantly CaCO₃ (calcite), with possible mica and quartz

Quartz-rich metamorphic rock, likely quartzite

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

Quartz–feldspar–mica metamorphic rock (likely gneiss)

Granitic gneiss; chiefly quartz (SiO₂), feldspar, and biotite/muscovite mica

Dark metamorphic rock, likely hornfels or fine-grained basalt

Probable hornfels; commonly quartz–feldspar–mica with variable amphibole/pyroxene

Vein-bearing metamorphic rock, likely gneiss or schist

Banded silicate rock; likely quartz–feldspar–mica gneiss with a quartz vein

Weathered quartz-rich metamorphic rock, likely quartzite

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

Likely foliated metamorphic rock (gneiss or schist)

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

Likely mica-rich metamorphic rock (schist)

Muscovite–biotite schist; composition commonly quartz + feldspar + mica

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-rich gneiss; exact identification requires a fresh surface and testing

Quartz-veined metamorphic rock, likely schist or gneiss

Quartz–feldspar–mica rock; exact identification requires testing

Iron-rich metamorphic rock, possibly micaceous schist

Biotite–quartz schist or iron-rich phyllite (tentative visual identification)

Quartz-veined dark metamorphic rock, likely schist or gneiss

Quartz-bearing mica schist/gneiss; mainly quartz (SiO₂), feldspar, mica, and iron-oxide staining

Dark metamorphic rock, likely schist or phyllite

Quartz–mica schist/phyllite; chiefly quartz, mica, and feldspar

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Quartz-rich metamorphic rock, likely quartzite

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

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with minor dark mica or amphibole and possible feldspar

Dark gray foliated metamorphic rock, likely slate or phyllite

Slate/phyllite; chiefly fine-grained mica and quartz, with possible chlorite and carbonaceous matter

Dark metamorphic rock, likely slate or phyllite

Foliated metapelite; commonly mica-rich quartz–clay mineral assemblage

Quartz-rich metamorphic rock, likely quartzite

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

Tumbled garnet-bearing metamorphic rock (probable garnet schist)

Garnet schist; chiefly quartz, mica, feldspar, and almandine garnet (Fe₃Al₂Si₃O₁₂)

Foliated metamorphic rock, likely slate or phyllite

Slate–phyllite; primarily quartz, mica, and clay-derived minerals

Iron-rich metamorphic rock, likely hematite-bearing schist or ironstone

Hematite/goethite-rich quartz–mica schist or banded ironstone; Fe₂O₃ and FeO(OH) are probable major iron minerals

Raw graphite-rich metamorphic rock (probable graphite schist)

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