Gneiss
Gneiss (High-grade Metamorphic Rock)
metamorphic
Category
Igneous Or Sedimentary (Anthropogenic Modification)
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Gneiss (with Quartz and Mica)
Gneiss
metamorphic
Coarse-grained metamorphic rock, likely gneiss or schist
Probable biotite-quartz-feldspar gneiss/schist; exact identification requires a fresh surface and tests
metamorphic
Banded metamorphic rock, likely gneiss
Foliated gneiss; chiefly quartz, feldspar, and dark mica/amphibole
metamorphic
Polished banded gneiss pebble
Gneiss, commonly quartz–feldspar–biotite gneiss
metamorphic
Polished gray stone, likely labradorite or gneiss
Indeterminate from image; possibly plagioclase-rich gneiss or labradorite-bearing rock
mineral
Banded Gneiss
Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Biotite/Amphiboles)
metamorphic
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
mineraloid
Gneiss
Gneiss
metamorphic
Druzy Quartz
Crystalline Silicon Dioxide (SiO2)
mineral
Banded gneiss pebble
Gneiss, commonly quartz–feldspar–biotite gneiss
metamorphic
Gneiss
High-grade foliated metamorphic rock
metamorphic
Banded Gneiss
Gneiss (High-grade metamorphic rock)
metamorphic
Slag (Industrial Byproduct)
Artificial silicate/iron byproduct
Mineral description (Anthropogenic material)
Banded gneiss pebble
Gneiss, chiefly quartz–feldspar–biotite (composition variable)
metamorphic
Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Gneiss
Gneiss (High-grade metamorphic rock)
metamorphic
Granite Gneiss River Rock
Gneiss
Metamorphic
Gneiss (River Cobble)
Metamorphic Gneiss
metamorphic
Gneiss
Gneiss
metamorphic
Green sea glass or green glass-like tumbled material
Amorphous silicate glass; likely anthropogenic soda-lime glass, not a natural mineral
mineral
Gneiss
Gneiss
metamorphic
Banded metamorphic pebble, likely gneiss
Foliated gneiss; quartz–feldspar–mica assemblage
metamorphic
Gneiss
High-grade metamorphic rock (Gneiss)
metamorphic
Banded Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Rounded river pebble, likely quartz-rich sandstone or fine-grained granite
Indeterminate from photograph; possible quartz/feldspar-bearing granitic pebble
igneous
Dendritic Agate
Silicon Dioxide (SiO2) with manganese/iron inclusions
mineral
Gneiss
Foliated Metamorphic Rock
metamorphic
Gneiss
Gneiss
metamorphic
Banded Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Gneiss (River Cobble)
Gneiss (Foliated Metamorphic Rock)
metamorphic
Banded metamorphic rock, likely gneiss or banded amphibolite
Undetermined foliated metamorphic rock; commonly quartz–feldspar–biotite gneiss or amphibolite
metamorphic
Agate Geode
Chalcedony (cryptocrystalline SiO2)
mineral
Blue-gray quartz-bearing metamorphic rock (likely gneiss or schist)
Quartz–feldspar–mica rock; exact identification requires testing
metamorphic
Gneiss (Metamorphic Rock)
Gneiss (high-grade regional metamorphic rock)
metamorphic
Gneiss
Metamorphic rock of high-grade regional metamorphism
metamorphic
Pyrite
Iron Sulfide (FeS2)
mineral
Polished banded stone, likely gneiss or metasedimentary rock
Banded gneiss (quartz–feldspar–mica assemblage; exact identification requires testing)
metamorphic
Gneiss
Metamorphic Gneiss
metamorphic
Gneiss (Banded Gneiss)
Gneiss
metamorphic
Quartz (Agate/Chalcedony variety)
Silicon Dioxide (SiO2)
mineral
Slag (Industrial Glass)
Artificial Vitreous Silicate
mineraloid (anthropogenic)