Metamorphic Rock

Gneiss

Gneiss (High-grade regional metamorphic rock)

Gneiss with Orthoclase Feldspar

Gneissic Metamorphic Rock with K-Feldspar inclusions

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Gneiss (specifically a granitic gneiss cobble)

Gneiss (high-grade regional metamorphic rock)

Mica Schist

Mica Schist (Intermediate-grade Metamorphic Rock)

Slate

Slate (Low-grade foliated metamorphic rock)

Yellow Quartzite Pebble

Metamorphic rock predominantly composed of Quartz (SiO2)

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Gneiss (specifically Granite Gneiss)

Gneiss (High-grade Regional Metamorphic Rock)

Granitic Gneiss

Gneiss (High-grade regional metamorphic rock)

Banded Gneiss (River Cobble)

Gneiss (High-grade regional metamorphic rock)

River Rock (likely Gneiss or Quartzite)

Metamorphic rock specimen (potentially Foliated Gneiss)

River Pebble (Gneiss or Granite)

Metamorphic Rock (likely Gneiss or Granitic composition)

Anthracite Coal

Anthracite (Carbon-based sedimentary-metamorphic rock)

Green Slate (Greenstone)

Foliated Metamorphic Rock (rich in Chlorite/Epidote)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Feldspathic Gneiss (Granite Gneiss)

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Weathered sandstone fragment

Quartz-rich sandstone (compositionally uncertain)

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; exact identification requires testing

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

Serpentinite (likely serpentinized ultramafic rock)

Serpentine-group minerals, chiefly antigorite/lizardite; commonly derived from peridotite

Serpentinite pebble

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with magnetite and accessory chlorite/talc

Likely polished basalt or iron-rich metamorphic rock

Basaltic rock, chiefly plagioclase and pyroxene; exact identification requires testing

Slate with Quartz Vein

Foliated Metamorphic Rock (Mainly Quartz, Muscovite, Chlorite)

Banded iron formation (iron-rich metamorphic rock)

Banded iron formation, chiefly hematite/magnetite with chert or quartz (Fe₂O₃/Fe₃O₄ + SiO₂)

Likely biotite schist or mica-rich metamorphic rock

Mica schist, predominantly biotite mica with quartz and feldspar

Banded iron formation (iron-rich metamorphic rock)

Banded iron formation (BIF), chiefly hematite/magnetite with chert or quartz (Fe₂O₃/Fe₃O₄ and SiO₂)

Quartz-veined Metamorphic Pebble

Silicate-rich metamorphic rock with quartz veins (SiO2)

Limonite pseudomorph after pyrite

Goethite / Limonite pseudomorph after Pyrite (Fe3+O(OH) replacing FeS2)

Lapis Lazuli

Na8[Al6Si6O24]Sn (Lazurite-rich metamorphic rock)

Iron-rich quartzite or quartz-bearing metamorphic rock

Quartzite, predominantly SiO₂, with iron-oxide staining (hematite/goethite)

Unakite

Unakite (Epidote-Feldspar rock)

Quartz in Greenstone

Metamorphic rock with quartz vein (SiO2 / mixed silicates)

Banded River Rock / Gneiss (highly weathered)

Gneiss

Dark gray crystalline rock, possibly mica-rich schist or graphite-bearing gneiss

Indeterminate; likely quartz–feldspar–mica metamorphic rock

Quartz Vein in Greenstone

Metamorphic rock with quartz vein (SiO2 / mixed silicates)