River Rock (likely Siltstone or fine-grained Sandstone)
Clastic Sedimentary Rock
sedimentary
Category
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Sandstone with Secondary Mineral Encrustation
Arenite with Silica/Calcite deposits (SiO2 or CaCO3)
sedimentary
Spessartine Garnet in Quartz/Feldspar Pegmatite
Spessartine (Mn3Al2(SiO4)3) in Quartz (SiO2) and Feldspar
Mineral in Igneous Rock
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Limestone (Calcium Carbonate: CaCO3)
sedimentary
Sandstone (likely Arkosic)
Arenite (SiO2 with KAlSi3O8)
sedimentary
Limestone (Weathered)
Calcium Carbonate (CaCO3)
sedimentary
Dyed Agate Slice
Silicon Dioxide (SiO2)
mineral
Granitic Pegmatite (with Smoky Quartz and Mica)
Granitic Pegmatite (composed of SiO2, KAl2(AlSi3O10)(OH)2, and (K,Na)(AlSi3O8))
igneous
Limonite (Ironstone Concretion)
Limonite: FeO(OH)·nH2O
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Sandstone (Lithic Wacke)
Clastic sedimentary rock (primarily SiO2 with rock fragments)
sedimentary
River Pebble (likely Quartzite or Diorite)
Metamorphosed Quartz-rich Rock / Intermediate Igneous Rock
metamorphic
River Rocks (Basalt and Sedimentary Stones)
Mafic Igneous Rock (Basalt) and Clastic Sedimentary Rock
igneous and sedimentary
Quartz Geode Segment
Crystalline Silicon Dioxide (SiO2)
mineral
Agate Geode Slice (with Druzy Quartz)
Silicon Dioxide (SiO2)
mineral
Granite Pebble
Intrusive Igneous Rock (Quartz, Feldspar, Mica)
igneous
Quartz Vein in Host Rock
Silicon dioxide (SiO2) veining in silicate matrix
sedimentary
Olivine Weathered Rock (Dunite)
Dunite ((Mg, Fe)2SiO4)
igneous
Basalt
Extrusive Igneous Rock
igneous
Fossil Coral
Rugosa or Tabulata coral fossil
fossil
Mixed Quartz and River Pebbles (Stone Collection)
Mixed assortment containing mainly Silicon Dioxide (SiO2)
igneous, sedimentary, metamorphic, and mineral
Granite
Felsic intrusive igneous rock
igneous
Granite
Intrusive Igneous Rock
igneous
Banded Agate
SiO2 (Silicon Dioxide)
mineral
Painted River Rock
Anthropogenic-modified Siliciclastic Sedimentary Rock
Sedimentary
Andesite Porphyry
Andesite (extrusive volcanic rock)
igneous
Granite (Background) and Quartzite/River Pebble (Foreground Heart)
Phaneritic Felsic Igneous Rock (Granite background)
igneous
Greenschist
Greenschist (chlorite-epidote schist)
metamorphic
Turquoise cabochon
Turquoise; hydrated copper–aluminum phosphate, approximately CuAl6(PO4)4(OH)8·4H2O (composition varies)
gemstone
Sandstone
Arenite (SiO2 based with cement)
sedimentary
Basalt Pebble
Extrusive Igneous Rock
igneous
Basalt (Vesicular/Weathered)
Mafic Igneous Rock (Mainly Plagioclase and Pyroxene)
igneous
Shale or Mudstone
Argillaceous sedimentary rock
sedimentary
Limestone
Carbonate rock (CaCO3)
sedimentary
Basalt Pebble
Extrusive Igneous Rock (Mafic)
igneous
Sandstone
Clastic Sedimentary Rock
sedimentary
Speckled granitic rock
Likely granite or granodiorite; quartz–feldspar–mica aggregate
igneous
Coral Fossil (Hexagonaria)
Hexagonaria sp. (Silica-replaced)
fossil
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Granite
Granite (Felsic Plutonic Rock)
igneous