Biotite–quartz–feldspar gneiss
Gneiss, composed chiefly of quartz (SiO₂), feldspar, and dark mica, likely biotite
metamorphic
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Peridotite (Olivine Rock)
Peridotite (composed largely of olivine, (Mg, Fe)2SiO4)
igneous
Black basalt
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, pyroxene, and commonly olivine
igneous
Rounded weathered rock, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; precise identification requires testing
igneous
Amethyst Quartz Druse
Silicon Dioxide (SiO2) with iron impurities
mineral
Sandstone
Arenite
sedimentary
Sandstone (lithic wacke/conglomerate mix)
Clastic Sedimentary Rock (SiO2 with lithic fragments)
sedimentary
Sandstone
Sandstone (arenite is a more specific geological term for a clean sandstone, while wacke refers to a dirty sandstone with significant matrix)
Sedimentary
Sandstone
Sandstone (various mineral compositions)
Sedimentary
Quartz Vein Rock with Feldspar
Silicon Dioxide (SiO2) with Potassium Feldspar
mineral
Porphyritic Andesite
Andesite with Hornblende phenocrysts
igneous
Basalt Pebble
Mafic Extrusive Igneous Rock
igneous
Sandstone
Arenite (primarily Quartz and Feldspar)
sedimentary
Granite
Granite (felsic intrusive igneous rock)
igneous
Conglomerate
Polymictic clast-supported conglomerate, likely ferruginous
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Chalcedony (Blue Dragon/Gray Chalcedony)
Silicon Dioxide (SiO₂)
mineral
Chert (or potentially Jasper/Chalcedony)
SiO2 (Silicon Dioxide)
sedimentary
Basalt Pebble
Extrusive Igneous Rock
igneous
Granite Pebble
Granite
igneous
Sandstone or Weathered Conglomerate
Sedimentary Rock (Quartzose Sandstone / Lithic Arenite)
sedimentary
Granite
Phaneritic Felsic Igneous Rock
igneous
Sandstone (River Rock)
Arenite (composed primarily of SiO2)
sedimentary
Serpentine
Antigorite, Lizardite, or Chrysotile (Mg, Fe)3Si2O5(OH)4
metamorphic
River Stone (Quartzite/Chert mixture)
Microcrystalline Quartz (SiO2)
sedimentary
N/A (Non-Geological Specimen)
N/A
Unable to identify - Image contains non-geological items
N/A
Schist
Schist
Metamorphic
Sandstone (Ferruginous)
Arenite (primarily SiO2 with iron oxide cement)
sedimentary
Fossil Coral
Rugose Coral / Hexagonaria (CaCO3)
fossil
Asphalt (Bituminous Pavement Bit)
Bitumen-bound aggregate (Petrochemical-bound composite)
sedimentary (anthropogenic/technogenic)
Limestone with Lichen/Moss
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (Ferruginous)
Arenite (primarily SiO2 with iron oxide cement)
sedimentary
Basaltic Tuff / Volcanic Breccia
Pyroclastic Breccia / Lithic Tuff
igneous
Rock Salt
Halite (NaCl)
mineral
River Rock
Polished Siliceous Rock / Quartzite Pebble
sedimentary
River Rock
Mixed composition, often quartzite, sandstone, or basalt
sedimentary
River Rock
Polished Quartzite / Silicified Sedimentary Rock
sedimentary
Conglomerate
Conglomerate (a clastic sedimentary rock)
Sedimentary Rock
Sandstone with Manganese Dendrites
Clastic Sedimentary Rock (SiO2 based with MnO2 inclusions)
sedimentary
Basalt
Extrusive mafic igneous rock
igneous
Basalt
Extrusive Igneous Rock
igneous