Porphyritic Andesite
Andesite (Porphyritic texture)
igneous
Category
Not A Natural Rock
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Small rounded pebble (rock type indeterminate)
Unidentified lithic pebble; specific composition cannot be determined from the image
sedimentary
Gravel and Sand Aggregate
Unconsolidated Clastic Sediment
sedimentary
Sandstone
Clastic Sedimentary Rock
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale
Shale (Lutite)
sedimentary
Granite Pebble
Intrusive Igneous Rock
igneous
Magnetite
Fe3O4
mineral
Shale
Argillaceous Rock
sedimentary
Small rounded pebble, likely porous volcanic rock
Possibly vesicular basalt or scoria; exact identification is not possible from the image alone
igneous
Pebble
Lithic fragment
sedimentary
Unknown brown-and-gold rock fragment
Undetermined; possibly iron-stained quartz, mica schist, or sulfide-bearing ore
mineral
Sandstone
Arenite
sedimentary
Cannonball Concretion
Calcite-cemented sandstone concretion
sedimentary
Pumice and Scoria
Vesicular Volcanic Rock (Pumice: Silicic / Scoria: Mafic)
igneous
Mica Schist
Mica Schist (Complex Silicate Rock)
metamorphic
Ironstone Nodule
Ferruginous Sandstone / Limonite Concretion
sedimentary
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Borehole Rock / Pierced Stone
Sedimentary rock with naturally eroded piddock clam boring (Hag Stone)
sedimentary
Painted Rock
Weathered Sedimentary Rock (Painted)
sedimentary
Yellow Quartz
Silicon Dioxide (SiO2)
mineral
Veined river pebble (likely metamorphic rock)
Likely quartz-veined slate or phyllite; exact identification requires closer examination
metamorphic
Rounded pebble, likely greenstone or altered basalt
Likely chlorite- or epidote-altered basalt; identification is uncertain from the image alone
igneous
Sandstone
Sedimentary Rock (Quartz arenite)
sedimentary
Conglomerate (puddingstone)
Polymict conglomerate; rounded pebbles and cobbles cemented in a finer matrix
sedimentary
Chert / Flint Nodule
Cryptocrystalline quartz (SiO2)
sedimentary
Sandstone
Arenite (Siliclastic sedimentary rock)
sedimentary
Black Beach Pebble / Basalt Pebble
Basalt / Mafic Volcanic Rock
igneous
Sandstone Pebble
Sedimentary Rock (Quartzose Sandstone)
sedimentary
Sandstone (or Weathered Limestone Pebble)
Arenite / Calcarenite
sedimentary
Limestone bedrock
Limestone, chiefly calcite (CaCO₃)
sedimentary
Dyed Quartzite
Metamorphosed Quartz (SiO2) with synthetic pigment
metamorphic
Basalt Pebble
Aphanitic Mafic Igneous Rock
igneous
Basalt Pebble
Aphanitic extrusive igneous rock
igneous
Quartzite Pebble
Metamorphic Quartz-rich Rock
metamorphic
Pumice
Volcanic glass / Pumiceous rock
igneous
Dragon Vein Agate
Chalcedony (Quartz) - SiO2
mineral
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
River Pebble
Quartzite pebble
sedimentary
Polished decorative stone spheres
Mixed material; individual spheres may be agate, jasper, quartz, or other ornamental minerals
mineral
Small brown-gray mineral fragment
Indeterminate; possibly weathered quartz-, feldspar-, or iron-oxide-bearing rock
mineral
Rounded pebble, likely fine-grained river stone
Unidentified lithic pebble; composition cannot be determined from the image
sedimentary