Chert (specifically Tan/Gray Chert)
Microcrystalline quartz (SiO2)
sedimentary
Category
Not A Rock (Synthetic Material)
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Sandstone Clast
Arenite (primarily SiO2)
sedimentary
Sandstone Pebble
Sedimentary Clastic Rock (Quartz Arenite)
sedimentary
Veined Pebble (Septarian or Quartz-Veined Chert/Basalt)
Silicon Dioxide (SiO2) veins in matrix
sedimentary
Sandstone (with Chert/Quartzite)
Arenite (SiO2 primarily)
sedimentary
Basalt
Basalt
igneous
Fossilized Gastropod Steinkern
Class Gastropoda internal mold
fossil
Chert (River Pebble with Liesegang Rings)
Microcrystalline Silicon Dioxide (SiO2)
sedimentary
Jasper
Silicon dioxide (SiO2)
sedimentary
Likely weathered quartz-rich stone or fossil fragment
Indeterminate; possibly quartz-bearing sandstone, iron-stained quartz, or a fragmentary fossil
mineral
Fossilized Bivalve Shell
Class Bivalvia (fossilized)
fossil
Poppy Jasper
Microcrystalline Quartz (SiO2) with mineral inclusions
sedimentary
K2 Stone
Azurite in Granite
igneous
Sandstone (Ferruginous)
Sandstone (primarily SiO2 with Iron Oxide cement)
sedimentary
Sandstone (Quartzose Sandstone)
Arenite (primarily SiO2)
sedimentary
Sandstone
Sedimentary Clastic Rock (Quartz arenite)
sedimentary
Sandstone (likely Ferruginous)
Arenite (SiO2 with iron oxide impurities)
sedimentary
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)
sedimentary
Sandstone (Calcareous Sandstone)
Calcareous Sandstone (primarily SiO2 with CaCO3 cement)
sedimentary
Sandstone
Arenite (primarily Quartz Arenite)
sedimentary
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Peridotite (Pyroxenite/Serpentinized Dunite)
Ultramafic Rock (consisting primarily of Olivine and Pyroxene)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Red Sandstone
Arenite (primarily Quartz with Hematite cement)
sedimentary
Fossiliferous Limestone
Bioclastic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Ferrochrome Slag
Anthropogenic silicate/oxide glass (Complex silicate matrix with Cr-Fe-Si inclusions)
Industrial byproduct (often confused with igneous rocks or meteorites)
Chert (Chalcedony/Agate variety)
Silicon Dioxide (SiO2)
sedimentary
Gneiss
Gneiss (High-grade metamorphic rock)
metamorphic
Weathered river pebble, likely quartz-rich sandstone or iron-stained quartzite
Provisional identification: quartz-rich sandstone/quartzite; exact composition cannot be confirmed from the image
sedimentary
Biotite Schist (likely)
Biotite Schist (rock), Biotite (mineral)
Metamorphic
Tumbled green aventurine (probable)
Quartzite dominated by quartz (SiO₂), with green mica/fuchsite or chlorite inclusions
mineral
Fulgarite
Fulgurite (Lechatelierite / Vitrified Sand)
igneous
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon dioxide (SiO2)
sedimentary
Chert (often called Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Rounded yellow-brown pebble
Likely iron-stained sandstone or quartz-rich river cobble
sedimentary
Unakite
Unakite (Metamorphosed granite)
metamorphic
Quartz geode
Quartz (SiO₂), likely drusy/microcrystalline quartz lining a geode cavity
mineral
Jasper and Basalt Pebble
Polymineralic lithic pebble
igneous and sedimentary
Thunder Egg (Agate Core)
Cryptocrystalline Quartz (SiO2) in Rhyolite/Perlite Matrix
mineral
Red Sandstone
Arenite (SiO2 with Fe2O3)
sedimentary
Red jasper-bearing breccia (probable)
Microcrystalline quartz (SiO₂) with iron-oxide coloration, in a brecciated host
mineral