Metamorphic Rock

Quartzite (or Engineered Quartz Stone)

SiO2 (Silicon Dioxide)

Likely dark green-gray metamorphic pebble

Indeterminate; possibly chlorite schist, serpentinite, or amphibolite

Quartzite

Metamorphic Quartzite (SiO2)

Polished river pebble, likely granite or granitic gneiss

Quartz–feldspar–mica aggregate; possibly biotite granite (compositionally near granite)

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Pyrite

Iron Sulfide (FeS2)

Mica Schist with Quartz

Mica Schist (primarily Muscovite or Biotite with Quartz)

Tiger's Eye

Pseudomorph of quartz after crocidolite (SiO2 with iron oxide inclusions)

Quartzite

Quartzite (SiO2)

Mica Schist

Schist (Mica-rich Metamorphic Rock)

Banded Gneiss / Veined Metamorphic Pebble

Metamorphic Rock with Quartz/Feldspar Veins

Likely galena-bearing ore

Galena (lead sulfide, PbS), possibly mixed with sulfide minerals

Quartzite with Feldspar and Mica (Granitic Gneiss Pebble)

Metamorphic Rock / Quartzite / Granitic Gneiss

Gneiss

High-grade metamorphic rock (Gneiss)

Unakite-like epidote–feldspar rock

Epidote + K-feldspar/plagioclase ± quartz; compositionally similar to unakite

Pink Marble

Recrystallized Limestone (Calcium Carbonate, CaCO3)

Anthracite Coal

Anthracite (Carbon Content: 86%-97%)

Granite Gneiss

Gneiss (High-grade Metamorphic Rock)

Garnet (Almandine)

Almandine, Fe3Al2(SiO4)3

Basalt cobble

Basalt; predominantly plagioclase, clinopyroxene, and often olivine or iron-titanium oxides

Eclogite

Eclogite (High-pressure metamorphic rock)

Gneiss

Gneiss (High-grade metamorphic rock)

Eclogite

Eclogite (Omphacite-Garnet Metamorphic Rock)

Tumbled reddish-brown basalt or andesite cobble

Fine-grained mafic to intermediate volcanic rock; commonly plagioclase, pyroxene, and magnetite, with iron-oxide staining

Gneiss

Gneiss (High-grade metamorphic rock)

Gneiss

Gneiss (High-grade metamorphic rock)

Gneiss

Gneiss (High-grade metamorphic rock)

Muscovite Mica Schist

Metamorphic Rock (Muscovite-Biotite Schist)

Lapis Lazuli (Tumbled)

Lazurite-dominated contact metamorphic rock

Gneiss

Gneiss (High-grade metamorphic rock)

Banded Gneiss

Gneiss (High-grade Metamorphic Rock)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Banded Gneiss

Gneiss (High-grade metamorphic rock)

Gneiss

Gneiss (High-grade metamorphic rock)

River Cobble (Gneiss/Schist mix)

Foliated Metamorphic Rock (Gneissic/Schistose)

Green Slate Pebble (Serpentine / Greenschist Pebble)

Greenschist / Low-grade Metamorphic Rock

Schist

Mica Schist (Foliated Metamorphic Rock)

Banded Gneiss

Gneiss (Felsic to Mafic Metamorphic Rock)

Gneiss with Quartz Veining

Gneiss (High-grade Regional Metamorphic Rock)

Mica Schist / Granite

Mica Schist (Silicate metamorphic rock)

Granitic Gneiss

Gneiss (High-grade metamorphic rock)

Gneiss

Gneiss (High-grade Metamorphic Rock)