Metamorphic Rock

Mica-rich metamorphic rock, likely schist

Biotite–muscovite schist, possibly quartz-mica schist

Tumbled dark metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar, with possible biotite and epidote

Iron-rich metamorphic rock, likely magnetite–hematite-bearing ironstone

Banded or massive iron formation (BIF), chiefly hematite (Fe₂O₃) and magnetite (Fe₃O₄), with quartz and possible iron silicates

Quartz-rich metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica metamorphic aggregate; exact identification requires thin-section or field tests

Quartz-veined dark metamorphic rock, likely marble or serpentinite

Calcite- or magnesite-veined serpentinite/marble; exact identification requires testing

Quartz-rich metamorphic rock, likely quartzite

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

Likely garnet-bearing metamorphic rock

Garnet amphibolite or garnet-bearing schist; probable almandine garnet (Fe₃Al₂Si₃O₁₂) with amphibole, mica, quartz, and feldspar

Likely biotite-rich metamorphic rock (mica schist)

Mica schist, chiefly quartz + biotite mica; possible pyrite or sulfide grains

Graphite-rich metamorphic rock (likely graphite schist)

Graphite schist; predominantly graphitic carbon (C) with mica and quartz

Quartz-rich metamorphic rock, likely quartzite

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

Banded metamorphic rock, likely schist or gneiss

Foliated quartz–feldspar–mica rock; exact mineral identification requires sampling

Quartz-rich metamorphic rock, likely quartzite

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

Weathered mica-rich metamorphic rock

Probable mica schist or micaceous quartzite; exact identification requires testing

Quartz-rich metamorphic rock, likely quartzite

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

Quartz-veined dark metamorphic rock

Likely quartz-mica schist or foliated basalt with a quartz vein

Dark metamorphic rock, likely slate or phyllite

Fine-grained foliated metamorphic rock; commonly dominated by quartz, mica, and chlorite

Weathered gray metamorphic rock, likely slate or phyllite

Foliated metapelite; commonly muscovite–quartz–chlorite, possibly with iron-oxide staining

Weathered red-and-green metamorphic rock

Probable epidote-amphibolite or altered schist; exact identification requires testing

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite; composition dominated by mica and quartz

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite (mostly SiO₂), possibly iron-stained metaconglomerate or quartz-rich gneiss

Mica-rich metamorphic rock, likely phyllite or schist

Quartz–mica schist/phyllite; chiefly muscovite or biotite mica with quartz and feldspar

Layered dark metamorphic rock, likely slate or phyllite

Slate/phyllite; predominantly fine-grained quartz, mica, and chlorite

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-veined metamorphic rock, chiefly SiO₂ with iron-oxide staining

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite (mostly SiO₂), possibly ferruginous mica-bearing quartzite

Quartz-rich metamorphic rock, likely quartzite

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

Quartz-rich metamorphic rock, likely quartzite

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

Gray metamorphic rock, likely slate or phyllite

Probably quartz–mica phyllite or fine-grained slate; exact identification requires testing

Gray metamorphic rock, likely slate or phyllite

Fine-grained foliated rock, probably quartz–mica slate/phyllite

Mica-rich metamorphic rock, likely biotite schist or phyllite

Quartz–feldspar–mica schist/phyllite; commonly containing biotite, muscovite, and minor sulfides

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

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), with minor 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

Quartz-rich metamorphic rock, likely quartzite

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

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Dark metamorphic rock, likely slate or phyllite

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

Dark gray foliated metamorphic rock, likely slate or phyllite

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

Quartz-veined metamorphic rock, likely schist or gneiss

Quartz–feldspar–mica rock; exact identification requires testing

Likely foliated metamorphic rock (gneiss or schist)

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

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