Metamorphic Rock

Milky quartz-bearing metamorphic rock, likely quartzite

Quartzite, composed predominantly of quartz (SiO₂), possibly with mica and feldspar

White quartz-rich metamorphic rock, likely quartzite

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

Likely foliated metamorphic rock (schist or gneiss fragment)

Mica schist–gneiss; chiefly quartz, feldspar, and mica

Foliated metamorphic rock, likely gneiss or schist

Biotite–quartz–feldspar gneiss/schist; exact identification requires mineral and texture testing

Likely biotite-bearing metamorphic rock (schist or gneiss)

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

Amber (likely a small rough amber piece)

Fossilized plant resin; amber is an organic mineraloid, not a crystalline mineral

Rounded gray pebble, likely basalt or fine-grained igneous rock

Probably basalt (plagioclase feldspar + pyroxene ± olivine)

Dark mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

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

Biotite–quartz–feldspar gneiss, possibly micaceous quartzite

Dark metamorphic rock, likely schist or slate fragment

Indeterminate; possibly biotite schist, chlorite schist, or slate

Quartz-rich metamorphic rock, likely quartzite

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

Banded metamorphic rock, likely gneiss or metasedimentary slate

Quartz–feldspar–mica gneiss (tentative), possibly containing iron-oxide veins

Quartz-rich metamorphic rock, likely quartzite

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

Dark gray veined metamorphic rock

Likely marble or quartzite; exact identification requires hardness and acid tests

Pyrite-bearing metamorphic rock (likely schist or quartzite)

Pyrite (FeS₂) in a quartz-rich host rock, possibly mica schist

Banded metamorphic rock, likely gneiss or banded amphibolite

Quartz–feldspar–biotite gneiss or amphibolite; exact identification requires thin-section or mineral tests

Quartz-bearing metamorphic rock, likely mica schist

Mica schist with quartz; commonly muscovite/biotite mica and SiO₂ quartz

Weathered mafic metamorphic rock, likely serpentinite or altered basalt

Probably serpentinized ultramafic rock; commonly dominated by serpentine-group minerals, with magnetite and altered pyroxene/olivine

Quartz-veined Metamorphic Rock (Wishing Stone)

Quartz-veined Metamorphic/Igneous Host Rock with Quartz Veinlets

Weathered quartz-rich metamorphic rock, likely quartzite

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

Pyrite-bearing dark metamorphic rock, likely schist or hornfels

Quartz–feldspar–mica matrix with pyrite (FeS₂); exact identification requires testing

Weathered gray metamorphic rock, likely slate or phyllite

Fine-grained foliated metamorphic rock; commonly quartz–mica–chlorite, possibly chlorite phyllite

Weathered mafic metamorphic rock, likely amphibolite

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

Foliated metamorphic rock, likely schist or gneiss

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

Weathered quartz-rich metamorphic rock (probable quartzite or quartz vein rock)

Quartz-dominant rock; chiefly SiO₂, with minor iron-oxide and mica/clay impurities

Quartz-rich metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; commonly containing biotite or muscovite

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly amphibolite-bearing

Quartz-bearing metamorphic rock, likely schist or quartzite

Quartz (SiO₂) in a mica-rich metamorphic matrix

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly quartz-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

Quartz-veined metamorphic rock, likely greenschist or altered metavolcanic

Chlorite–actinolite–epidote-bearing metavolcanic rock with quartz veins; exact identification requires testing

Dark mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-mica schist; predominantly SiO₂ quartz with iron-oxide staining

Likely mica-rich metamorphic rock (schist/phyllite)

Muscovite–quartz–feldspar schist, possibly chlorite schist

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 foliated amphibolite

Quartz–feldspar–mica gneiss or amphibolite; exact identification requires testing

Weathered metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification is uncertain from the photograph

Foliated metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly migmatitic gneiss

Garnet-bearing metamorphic rock, likely mica schist

Biotite–garnet schist; commonly includes quartz, feldspar, biotite, and almandine garnet

Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins

Quartz-veined metamorphic rock (Silicate mineral assemblage)

Weathered quartz-rich metamorphic rock, possibly quartzite or gneiss

Quartz-dominant silicate rock; likely quartz (SiO₂) with feldspar, mica, and minor iron-oxide staining