Granite (Dioritic variant)
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
igneous
Category
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Hag Stone
Siltstone or Fine-grained Sandstone with boring (e.g., Lithophaga impact)
sedimentary
Liesegang Banded Sandstone (Concretion / Weathered Pebble)
Sandstone showing Liesegang rings / Weathering rind (SiO2 with iron oxides)
sedimentary
Brecciated Jasper
SiO2 (Silicon Dioxide)
sedimentary
Conglomerate (Asphaltic/Anthropogenic)
Clastic sedimentary rock / Bituminous mixture
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
gemstone
Amethyst Gemstone
Crystalline Quartz (SiO2 with iron impurities)
gemstone
River Stone (Quartzite/Basalt)
Variable; often Quartzite (SiO2) or Basaltic rock
metamorphic
Limestone (specifically Travertine or Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (with Possible Iron Staining/Crust)
Arenite (SiO2 based)
sedimentary
Agate
Silicon Dioxide (SiO2)
sedimentary
Sandstone
Arenite (typically SiO2 based)
sedimentary
Granite
Phaneritic Felsic Igneous Rock
igneous
Sandstone
Arenite (SiO2 primarily)
sedimentary
Porphyritic Basalt or Spotted Pebble
Porphyritic volcanic rock with phenocrysts
igneous
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone
Arenite
sedimentary
Sandstone (lithic wake or graywacke)
Clastic sedimentary rock (primarily quartz and lithic fragments)
sedimentary
Beach Pebble / Agate-bearing Chert Pebble
Microcrystalline Quartz (SiO2) with Inclusion Minerals
sedimentary
Yellow Chert (Yellow Jasper)
Silicon dioxide (SiO2)
sedimentary
Hag Stone (Adder Stone / Geode-bearing Pebble)
Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)
sedimentary
Jasper pebble
Silicon Dioxide (SiO2 with iron oxide inclusions)
sedimentary
Green Quartzite / Quartz Pebble
SiO2 (Silicon Dioxide with inclusions)
metamorphic
Vesicular Basalt (Scoria)
Mafic Igneous Volcanic Rock
igneous
River Pebble (Basalt or fine-grained Quartzite)
Fine-grained Mafic Rock (Volcanic Basalt)
igneous
Garnet (Almandine/Pyrope series)
Garnet Group - X3Y2(SiO4)3
mineral
Chalk
Calcium carbonate (CaCO3)
sedimentary
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Pumice
Pumice (Felsic volcanic glass)
igneous
Chert (Commonly known as Flint/Jasper)
Microcrystalline Quartz (SiO2) with iron oxide inclusions
sedimentary
Quartz Pebble (Feldspathic / Chert Pebble)
Silicon Dioxide (SiO2) / Potassium Feldspar (KAlSi3O8)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone
Arenite
sedimentary
Hag Stone
Perforated sedimentary rock (typically flint, chert, or limestone)
sedimentary
Asphalt Concrete
Bituminous conglomerate
sedimentary
Pumice
Vesicular volcanic glass (primarily SiO2)
igneous
Sandstone
Sandstone (SiO2 dominated)
sedimentary
Not a rock
Not a rock
Not a rock
Not a rock
Not a rock
Not a rock
Sandstone
Arenite (SiO2 principal composition)
sedimentary
Sandstone
Arenite (SiO2 principal)
sedimentary
Sandstone Flagstone
Arenite (SiO2 with various cementing agents)
sedimentary