Metamorphic Rock

Greenstone (likely chlorite-rich greenschist)

Greenschist facies metamorphic rock, typically composed of chlorite, actinolite, and albite; exact identification requires testing

Epidote (Unakite component) / Green Quartzite

Ca2(Al,Fe)3(SiO4)3(OH)

Granite-like gneiss

Foliated granitic gneiss, composed mainly of quartz, feldspar, and mica

Quartz-rich granitic rock (likely weathered granite)

Granite; chiefly quartz, feldspar, and mica, with possible iron-oxide staining

Polished fossil coral

Fossilized coral, commonly agatized coral (silica replacing CaCO₃)

Likely weathered fossil shell or fossiliferous limestone

Indeterminate molluscan fossil, possibly a bivalve or brachiopod preserved in carbonate rock

Weathered granitic gneiss or granite cobble

Granite–gneiss, chiefly quartz, feldspar, and dark mica/amphibole

Likely gray sandstone or fine-grained metamorphic rock

Quartz-rich lithic sandstone; exact identification is uncertain from the photograph

Quartz-veined Metamorphic Rock

Quartz Vein in Phyllite or Schist (SiO2 in Silicate Matrix)

Quartz vein in metamorphic rock

Crystalline Silicon Dioxide (SiO2) in Host Rock

Quartzite

Quartzite (SiO2 with minor impurities)

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Quartzite with Iron Inclusions

Quartzite (SiO2 with Fe2O3 impurities)

Banded Metamorphic Rock (likely Quartzite or Serpentinite/Soapstone)

Metamorphic Rock (possibly a banded Quartzite or a foliated Serpentinite/Talc Schist based on appearance, general term for such a rock is 'Banded Metamorphic Rock' or 'Gneiss' if pronounced banding of different minerals)

Gneiss (foliated metamorphic rock)

Gneiss

Rounded gray metamorphic cobble, likely quartzite or gneiss

Quartz-rich metamorphic rock; possibly quartzite (mostly SiO₂) or banded gneiss

Quartz-rich granitic cobble

Granite or granitic gneiss; primarily quartz, feldspar, and mica

Rounded sedimentary pebble, likely mudstone or shale

Argillite/mudstone; predominantly compacted clay minerals with quartz and iron oxides

Tumbled dark gray stone, likely basalt

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Quartz Vein in Metamorphic Rock

Silicon Dioxide (SiO2) within Metasedimentary host

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene, possibly olivine)

Sandstone pebble

Sandstone (arenite / quartzarenite)

Banded Slate

Slate (Metamorphosed Siltstone/Mudstone)

Mica Schist

Schist (Mica-rich Metamorphic Rock)

White marble (likely calcitic marble)

Calcite-rich marble; primarily calcium carbonate, CaCO₃

Tumbled purple stone, likely amethyst-bearing quartzite or dyed quartz

Quartz (SiO₂), possibly microcrystalline quartzite; purple color may be from iron-related amethyst or artificial dye

Granite (likely biotite granite or granodiorite)

Granitoid; mainly quartz, feldspar, and biotite/hornblende

Rounded quartz-rich sandstone pebble

Quartz arenite (sandstone), composition mainly SiO₂ with minor feldspar, mica, and iron-oxide cement

Mixed tumbled river pebbles and beach stones

Polymictic alluvial gravel; components include quartz, chert, jasper, sandstone, and altered volcanic rocks

Quartzite with Feldspar and Mica (Granitic Gneiss Pebble)

Metamorphic Rock / Quartzite / Granitic Gneiss

Gneiss

High-grade metamorphic rock (Gneiss)

Eclogite

Eclogite (Omphacite-Garnet Metamorphic Rock)

Garnet Schist

Mica Schist with Almandine (Fe3Al2(SiO4)3)

Unakite

Epidotized Granite

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Granite Gneiss

Gneiss (High-grade Metamorphic Rock)

Banded Gneiss / Veined Metamorphic Pebble

Metamorphic Rock with Quartz/Feldspar Veins

Red-and-gray granitic gneiss

Gneiss, composed mainly of quartz, feldspar, and mica with iron-oxide staining

Slate

Foliated Metamorphic Rock (composed primarily of Quartz, Muscovite, and Illite)

Gneiss

Gneiss (High-grade metamorphic rock)

Rounded gray stone, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; likely basalt (plagioclase ± pyroxene, possibly olivine)

Rough garnet-bearing rock, likely almandine garnet in matrix

Almandine garnet, Fe₃Al₂(SiO₄)₃; exact host rock cannot be determined from the image