Riverstone (likely Graywacke or Siltstone)
Sedimentary sandstone (Graywacke), SiO2 dominant
sedimentary
Category
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Sandstone
Arenite (SiO2 principal)
sedimentary
Sandstone
Arenite (Siliclastic sedimentary rock)
sedimentary
Sandstone (Pebble)
Arenite (composed primarily of SiO2)
sedimentary
Diorite (River Pebble)
Intermediate Phaneritic Igneous Rock
igneous
Lightning Stone / Fulgurite-impregnated or Septarian-like Agate
Silicon dioxide (Quartz/Chalcedony) with host rock matrix
sedimentary
Sandstone Pebble with Mineral Encrustation
Quartz Sandstone with Calcite/Halite Crust
sedimentary
Sandstone
Sedimentary rock composed mainly of quartz sand
sedimentary
Shale
Shale (claystone/mudstone)
sedimentary
Sandstone (with vugs or solution cavities)
Arenite (primarily Quartz and Feldspar with CaCO3 or SiO2 cement)
sedimentary
Granite
Intrusive Igneous Rock
igneous
Granite
Intrusive Igneous Rock
igneous
Granite
Intrusive Igneous Rock
igneous
Limestone
Calcareous sedimentary rock (CaCO3)
sedimentary
Shale
Argillite / Shale
sedimentary
River Pebbles (Chert and Quartzite)
Sedimentary Clastic Rock (Silica-rich)
sedimentary
Painted Rock
Weathered Sedimentary Rock (Painted)
sedimentary
Shale
Sedimentary Shale
sedimentary
Yellow Quartz Pebble (Citrine or Iron-Stained Quartz)
Silicon Dioxide (SiO2)
mineral
Druzy Quartz on Matrix
Silicon Dioxide (SiO2) on host rock
mineral
Shale
Argillaceous Rock
sedimentary
Dyed Quartz Pendant
Silicon Dioxide (SiO2) with artificial dye
mineral
Sandstone
Quartzose Sandstone (Sedimentary Rock)
sedimentary
Red Sandstone
Sandstone (Quartz Arenite / Arkose with Hematite cement)
sedimentary
Heart-shaped Limestone
Calcium Carbonate (CaCO3)
sedimentary
Quartzite pebble
Quartzite (SiO2)
metamorphic
Seashell Fossil
Invertebrate Bivalve / Gastropod Fossil (Calcium Carbonate, CaCO3)
fossil
Sandstone pebble
Sandstone (SiO2 with iron oxides)
sedimentary
Decorative polished pebbles
Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt
mineral
Granite
Phaneritic Plutonic Felsic Rock
igneous
Sandstone (likely Arkosic)
Clastic Sedimentary Rock (primarily SiO2 with Feldspar)
sedimentary
Chert (or Flint)
Chert (cryptocrystalline quartz), SiO2
Sedimentary
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Granite
Phaneritic Felsic Intrusive Igneous Rock
igneous
Lapis Lazuli
Lapis Lazuli (a rock, not a single mineral; primary mineral is Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2
Metamorphic rock
Diorite
Diorite (Plagioclase feldspar and amphibole/biotite)
igneous
Sandstone
Arenite
sedimentary
Basalt
Basalt (comprising Plagioclase feldspar, Pyroxene, and Olivine)
igneous
Chert (Nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Heart-shaped Quartz
Silicon Dioxide (SiO2)
mineral
Green Aventurine
Quartz (SiO2) with Fuchsite inclusions
Mineral