Granite pebble
Granite, chiefly quartz, feldspar, and mica
igneous
Category
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Reddish-brown rounded pebble, likely iron-stained sandstone or chert
Probable quartz-rich sandstone (SiO₂), possibly ferruginous chert; exact identification requires testing
sedimentary
Quartzite
Metamorphic Quartzite (predominantly SiO2)
metamorphic
Ferruginous Quartz Cobble
Silicon Dioxide (SiO2) with Iron Oxide inclusions
mineral
Sandstone
Clastic sedimentary rock (primarily Quartz and Feldspar)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Tumbled greenish jasper
Jasper, microcrystalline quartz (SiO₂) with iron-bearing and clay-mineral impurities
metamorphic
Sandstone
Sedimentary Rock (Quartz arenite / Lithic sandstone)
sedimentary
Tumbled black-and-white stone, likely dendritic agate or jasper
Cryptocrystalline quartz (SiO₂), possibly chalcedony with manganese-oxide dendrites
mineral
Sandstone (with Iron Staining)
Clastic Sedimentary Rock (primarily Quartz, SiO2)
sedimentary
Red Sandstone
Arenite (SiO2 based with Fe2O3)
sedimentary
Granite
Granite (Phaneritic Quartz-Feldspar rock)
igneous
Sandstone (Red Sandstone)
Arenite (primarily Quartz with Hematite cement)
sedimentary
Slag
Glassy silicate byproduct (anthropogenic material)
industrial byproduct
Petrified Wood
Silicified wood (primarily Quartz, SiO2)
fossil
Basalt
Basalt (Mafic volcanic rock)
igneous
Weathered sandstone or limestone fragment
Likely quartz-rich sandstone or micritic limestone; exact identification requires testing
sedimentary
Chert (varietal Flint)
Microcrystalline quartz (SiO2)
sedimentary
Basalt
Basalt (Igneous Volcanic)
igneous
Fossilized Bivalve Shell
Bivalvia (Phylum Mollusca)
fossil
Quartzite Pebble
Metamorphic Quartzite
metamorphic
Milky Quartz Geode / Chalcedony Nodule
Quartz (Silicon Dioxide - SiO2)
mineral
Granite or granitic rock fragment
Felsic intrusive igneous rock, typically quartz + feldspar + mica; exact species uncertain from the image
igneous
Smelter Slag
Anthropogenic Silicate Slag
igneous
Fossilized Coral (Coquina/Limestone)
Cnidaria Anthozoa (Fossilized)
sedimentary
Quartzite
Quartzite (Silicon Dioxide, SiO2)
metamorphic
Sandstone
Arenite (SiO2 principal)
sedimentary
Weathered granite or granitic gneiss
Granite; predominantly quartz, feldspar, and mica, possibly altered to gneiss
igneous
Chert (variously Flints)
Microcrystalline Quartz (SiO2)
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Chert (often called Flint or Jasper)
Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)
sedimentary
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Greenstone (River Pebble)
Metabasalt / Greenschist
metamorphic
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Quartz (specifically Milky/Gray Quartz vein)
Silicon Dioxide (SiO2)
mineral
Sandstone (Ferruginous)
Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 staining)
sedimentary
Rounded gray metamorphic cobble, likely quartzite or gneiss
Quartz-rich metamorphic rock; possibly quartzite (mostly SiO₂) or banded gneiss
metamorphic
Limestone
Sedimentary Calcite (CaCO3)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (Ferruginous)
Arenite (with iron oxide cement)
sedimentary
Basalt
Basalt (principally Plagioclase and Pyroxene)
igneous