Igneous And Sedimentary

Banded gneiss (likely weathered paragneiss)

Gneiss; quartz–feldspar–mica ± amphibole assemblage

Banded metamorphic rock, likely gneiss or banded amphibolite

Undetermined foliated metamorphic rock; commonly quartz–feldspar–biotite gneiss or amphibolite

Gneiss (rounded cobble)

Quartz–feldspar–mica gneiss; exact mineral proportions cannot be determined from the image

Biotite-bearing gneiss

Mica gneiss, composed mainly of quartz, feldspar, and biotite mica

Worn quartz-rich pebble

Likely microcrystalline quartz (SiO₂), possibly a weathered chert or milky quartz fragment

Banded Gneiss

Metamorphic Gneiss (High-grade regional metamorphism specimen)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Quartz Druze on Matrix (Geode Fragment)

Quartz (Silicon Dioxide, SiO2)

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss (High-Grade Metamorphic Rock)

Gneiss (primarily composed of Quartz, Feldspar, and Mica/Amphiboles)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Carnelian

Carnelian (SiO2, Silicon Dioxide with Iron Oxide impurities)

Gneiss (specifically a Banded Gneiss cobble)

Gneiss (composed mainly of Quartz, Feldspar, and Biotite/Amphibole)

Gneiss

Gneiss

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss (Schistose)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Gneiss (Metamorphic silicate rock)

Carnelian

Carnelian (Silicon Dioxide - SiO2)

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Carnelian

Cryptocrystalline Quartz (SiO2 with iron oxide impurities)

Banded Gneiss

Gneiss (Metamorphic Rock)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Banded Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Biotite/Amphiboles)

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly amphibolite-bearing

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–biotite gneiss

Banded gneiss

Gneiss, commonly quartz–feldspar–mica gneiss

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Banded gneiss pebble

Gneiss, a foliated metamorphic rock, likely quartz–feldspar–mica gneiss

Gneiss (probable)

Quartz–feldspar–mica gneiss; exact mineral composition cannot be confirmed from the image

Banded Gneiss and Siltstone River Stones

Gneiss (High-grade Metamorphic Rock)

Gneiss

Metamorphic Gneiss

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Gneiss

Gneiss

Gneiss

High-grade Metamorphic Gneiss

Banded Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica)

Banded gneiss

Foliated quartz–feldspar gneiss, likely biotite-bearing

Labradorite-bearing gneiss or schist

Feldspathic gneiss/schist containing iridescent labradorite (plagioclase feldspar, NaAlSi₃O₈–CaAl₂Si₂O₈)

Banded Gneiss

Gneiss (High-grade metamorphic rock)

Druzy Quartz (on Geode Fragment)

Silicon Dioxide (SiO2)

Quartz (Milky/Gravel variety)

Silicon Dioxide (SiO2)

Brown Chalcedony (Agate/Jasper blend)

Silicon dioxide (SiO2)

Banded gneissic rock

Gneiss, likely quartz–feldspar–biotite gneiss