Sandstone (Ferruginous)
Arenite (primarily SiO2 with Fe2O3 staining)
Category
Browse sedimentary rock (specifically a concretion or possibly a geode) specimens identified by the Rock Identifier community.
Sandstone (Ferruginous)
Arenite (primarily SiO2 with Fe2O3 staining)
Amygdaloidal Basalt
Amygdaloidal Basalt containing Zeolite or Quartz (SiO2/Silicates)
Basalt Pebble
Basalt (Extrusive Mafic Igneous)
Pumice
Highly vesicular rhyolite/dacite (Amorphous glass)
Basalt with Scoria/Vesicular Texture
Extrusive Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
Basalt (River-worn Specimen)
Extrusive Mafic Igneous Rock
Basalt (Porphyritic)
Basalt (Mafic Extrusive Igneous Rock)
Pumice
Pumice (Vesicular Volcanic Glass)
Amber
Succinite (specifically for Baltic amber); chemical formula approximately C10H16O
Sandstone
Arenite
Sandstone (Quartzose Sandstone)
Arenite (primarily SiO2)
Limonite (after Pyrite Pseudomorph)
Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)
Magnetite / Iron Ore
Magnetite (Fe3O4)
Rutilated Quartz
Quartz (SiO2) with Rutile (TiO2) inclusions
Sandstone
Arenite
Quartz (likely a macrocrystalline variety like milky quartz or smoky quartz, given the appearance in the image)
Quartz (SiO₂ - Silicon Dioxide)
Basalt (Water-worn pebble)
Basalt (Aphanitic mafic volcanic rock)
Granite
Phaneritic plutonic rock (Quartz, Feldspar, Mica)
Sandstone
Arenite
Basalt
Basalt (Aphanitic Mafic Volcanic)
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
Gneiss
High-grade metamorphic rock (Gneiss)
Sandstone
Arenite (Sedimentary rock composed of sand-sized grains, primarily SiO2)
Sandstone Cobble
Clastic Sedimentary (Sandstone)
Pebble (Likely Basalt or Siltstone)
Clastic sedimentary rock or mafic volcanic rock
Sandstone
Arenite (SiO2 based)
Sandstone
Arenite
Pumice
Vesicular volcanic glass (Amorphous silica mixed with various oxides)
Banded Chert
Microcrystalline Quartz (SiO2)
Chert (Jasper/Mudstone variant)
Silicon Dioxide (SiO2)
Quartz
Quartz (SiO₂ - Silicon Dioxide)
Sandstone
Arenite (primarily SiO2)
Painted River Rock
Anthropogenic-modified Siliciclastic Sedimentary Rock
Porphyritic Andesite
Intermediate Volcanic Rock - Andesite
Basalt Pebble
Basalt (Mafic volcanic rock)
Basalt
Aphanitic Mafic Igneous Rock
Slag
Ferrous Slag (Amorphous calcium-magnesium-aluminum silicates)
Vesicular Basalt (or Porphyritic Scoria)
Vesicular Basalt
Pumice
Pumice (volcanic glass formed of highly vesicular rough textured rock)
Shale
Shale (composition varies: primarily clay minerals and quartz)
Gneiss
High-grade regional metamorphic rock (Foliated)
Sandstone (likely Arkosic)
Arenite (SiO2 with KAlSi3O8)