Sandstone (Pebble / Cobble)
Arenite / Sedimentary Rock (composed of quartz and feldspar)
sedimentary
Category
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Beach Pebble (Chalcedony / Chert)
Silicon Dioxide (SiO2)
mineral
Sandstone (with potential iron mineralization)
Arenite
sedimentary
Pyritic Mudstone
Argillaceous rock (FeS2)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Sandstone (with banding/weathering)
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Dark basalt or basaltic volcanic rock
Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and often olivine
igneous
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)3Si2O5(OH)4
metamorphic
Sandstone
Arenite (primarily SiO2)
sedimentary
Tumbled red jasper
Jasper, microcrystalline quartz (SiO₂), commonly colored by iron oxides
mineral
Granite
Granite (Phaneritic Igneous Rock)
igneous
Dalmatian Stone and Lapis Lazuli
Dalmatian Stone (peralkaline rock) with Lapis Lazuli (metamorphic rock)
igneous
Banded Chert
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (Nodule)
Microcrystalline quartz (SiO2)
sedimentary
Polished opal-like chalcedony
Cryptocrystalline silica, SiO₂; likely common opal or pale chalcedony, with identification limited by the photograph
gemstone
Red Sandstone
Sandstone (Quartz Arenite with Iron Oxide)
sedimentary
Sandstone
Arenite
sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3)
sedimentary
Granite Pebble
Intrusive Igneous Rock (Felsic to Intermediate)
igneous
Sandstone (likely Quartzose)
Arenite (SiO2 principal mineral)
sedimentary
Serpentine / Serpentinite
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
metamorphic
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Red Sandstone
Arenite (with Iron Oxide)
sedimentary
Sandstone (Quartzose Sandstone)
Clastic sedimentary rock (SiO2 major component)
sedimentary
Sandstone Cobble
Arenite (Secondary classification based on grain size)
sedimentary
Sandstone
Sandstone (clastic sedimentary rock composite)
sedimentary
Quartzite (Pink / Peach)
SiO2 (Metamorphosed Quartz Sandstone)
metamorphic
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
metamorphic
Sandstone (with Iron Staining)
Clastic Sedimentary Rock (primarily Quartz with Fe2O3 staining)
sedimentary
Sandstone (Quartzose Sandstone)
Arenite (composed primarily of SiO2)
sedimentary
Granite
Intrusive Igneous Rock
igneous
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Quartzite
Quartzite (SiO2 with minor impurities)
metamorphic
Porphyry (Porphyritic Basalt / Porphyritic Andesite)
Porphyritic Igneous Rock
igneous
Sandstone (likely Graywacke or Lithic Sandstone)
Clastic Sedimentary Rock
sedimentary
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Sandstone (lithic/arkosic)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Sandstone with Vitrinite/Coal inclusions
Arenite with Carbonaceous inclusions
sedimentary
Sandstone
Sedimentary Clastic Rock (Quartz Arenite)
sedimentary
Jasper and Quartz Breccia
Silica breccia (SiO2)
sedimentary
Sandstone
Clastic sedimentary rock (Quartz arenite)
sedimentary