Metamorphic Rock

Gneiss (Metamorphic Rock)

Gneiss

Gneiss (Metamorphic Rock)

Gneiss (variable mineral formula primarily containing Quartz, Feldspar, and Mica)

Serpentine-rich metamorphic rock

Serpentinite, likely antigorite/lizardite with accessory magnetite or chromite

Green Slate or Metamorphic Rock

Metamorphic rock (chlorite/actinolite-bearing)

Dark weathered igneous rock, likely basalt

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

Pyrite Schist

Metamorphic rock containing FeS2 (Pyrite) with mica and quartz

Mixed river stones; foreground likely sandstone

Quartz-rich sandstone, with associated rounded quartzite/chert and other cobbles

Dark metamorphic rock, possibly amphibolite

Amphibolite (tentative; commonly hornblende and plagioclase)

Tumbled garnet-bearing gneiss

Gneiss containing almandine–pyrope garnet, quartz, feldspar, and mica

Quartz Vein in Metamorphic Rock

Quartzite or Schist host with Quartz (SiO2) intrusion

Weathered metamorphic rock, likely gneiss or schist

Indeterminate foliated silicate rock; commonly quartz–feldspar–mica assemblage

Galena-bearing metamorphic rock (tentative)

Likely galena (PbS) with quartz and/or carbonate matrix; exact identification requires testing

Weathered foliated metamorphic rock, likely schist or gneiss

Micaceous schist/gneiss; composition likely quartz, feldspar, mica, and altered mafic minerals

Quartz-veined metamorphic rock

Likely quartz-veined schist or gneiss; exact identification requires closer examination

Weathered foliated metamorphic rock, likely gneiss or schist

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

Weathered gneissic metamorphic rock

Gneiss, likely quartz–feldspar–mica gneiss

Weathered banded metamorphic rock, likely gneiss

Banded gneiss; commonly quartz–feldspar–mica assemblage

Likely weathered metamorphic rock (quartzite or schist)

Quartz-rich foliated metamorphic rock; exact identification requires testing

Quartz-bearing metamorphic rock, possibly epidote/quartzite

Quartz-rich rock with possible epidote and feldspar; exact identification requires testing

Garnet-bearing metamorphic rock

Likely garnet schist or garnet amphibolite; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Unidentified gray metamorphic rock, likely schist or gneiss

Quartz–feldspar–mica metamorphic rock; exact identification requires testing

Quartz-bearing metamorphic rock, possibly quartzite or hornfels

Mostly quartz (SiO₂), with probable iron-oxide and dark silicate minerals

Weathered foliated metamorphic rock, likely schist or gneiss

Micaceous quartz–feldspar metamorphic rock; exact mineralogy requires testing

Green Slate or Metamorphic Rock with Moss/Lichen

Metamorphic rock / Phyllite or Slate variant

Metamorphic rock with large feldspar crystals (likely porphyroblastic gneiss)

Feldspar-porphyroblastic gneiss; likely quartz and feldspar with mica/amphibole, identification from image only

Dark metamorphic rock, likely biotite-rich schist or amphibolite

Biotite–quartz–feldspar schist/amphibolite; exact identification requires testing

Garnet-bearing metamorphic rock

Garnet amphibolite or garnet–mica schist; chiefly almandine garnet (Fe₃Al₂Si₃O₁₂) with amphibole, mica, quartz, and feldspar

Foliated metamorphic rock, likely biotite schist

Mica schist, chiefly quartz, feldspar, and biotite mica

Garnet-bearing metamorphic rock, possibly garnet amphibolite or mica schist

Almandine garnet (Fe₃Al₂Si₃O₁₂) in a mafic, amphibole–feldspar-rich matrix

Serpentine-rich metamorphic rock (probable serpentinite)

Serpentinite; chiefly antigorite, lizardite, or chrysotile [Mg3Si2O5(OH)4], with possible talc, carbonate, magnetite, and remnant olivine/pyroxene

Foliated metamorphic rock, likely garnet-mica schist

Mica schist with probable garnet and quartz; exact identification requires testing

Reddish foliated metamorphic rock, likely phyllite

Phyllite, typically quartz–mica–chlorite with iron-oxide staining

Weathered greenish metamorphic rock, possibly serpentinite

Serpentinite; chiefly serpentine-group minerals, commonly Mg₃Si₂O₅(OH)₄, with possible magnetite and chlorite

Weathered greenish metamorphic rock, possibly serpentinite

Serpentinite, commonly dominated by antigorite/lizardite Mg₃Si₂O₅(OH)₄; identification is uncertain from the photograph

Graphite-rich metamorphic rock (graphitic schist)

Graphitic schist; chiefly graphite (C), quartz (SiO₂), and mica minerals

Serpentine-rich metamorphic rock

Serpentinite, likely with quartz or calcite veining and minor magnetite

Weathered greenish metamorphic rock, likely serpentinite

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

Rhodonite-bearing metamorphic rock

Rhodonite (MnSiO₃) with quartz and dark manganese oxides, likely a manganiferous schist or breccia

Foliated metamorphic rock (likely phyllite or fine-grained schist)

Phyllite–schist, chiefly quartz, mica, and clay-derived silicates

Weathered foliated metamorphic rock, likely schist or gneiss

Mica schist to gneiss; commonly quartz + feldspar + biotite/muscovite

Likely foliated metamorphic rock (quartz-mica schist or gneiss)

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

Graphite-bearing metamorphic rock (probable graphite schist)

Graphite schist; predominantly quartz–mica–graphite, with possible feldspar and sulfide minerals