Snowflake Obsidian
Spherulitic Obsidian (Amorphous Volcanic Glass with Cristobalite inclusions)
igneous
Category
Organic (Non Rock)
Browse organic (non rock) specimens identified by the Rock Identifier community.
Learn about Organic (Non Rock) in the encyclopedia
View all →
White Precious Opal
Hydrated Silica (SiO2·nH2O)
mineral
Fossiliferous Limestone
Calcium Carbonate (CaCO3)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Fossilized Coral (Petrified Coral)
Lithostrotionella (example genus) / Scleractinia
fossil
Chert (River Cobble)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Travertine
Travertine (a terrestrial form of Limestone, CaCO3)
sedimentary
Basalt (River Pebble)
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Sandstone Pebble
Arenite (primarily SiO2)
sedimentary
Fossiliferous Limestone
Biogenic Sedimentary Rock (primarily CaCO3)
sedimentary
Quartzite
Quartzite (Metamorphic rock primarily composed of SiO2)
metamorphic
Bauxite
Bauxite (Al2O3·2H2O mixed with iron oxides)
sedimentary
Fossilized stromatolite or laminated microbial mat
Layered carbonate/chert fossil; exact taxon indeterminate from the image
fossil
Chert (Chert Nodule with Chalky Cortex)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (Nodule)
Microcrystalline quartz (SiO2)
sedimentary
Concretion or weathered iron-rich rock
Likely limonite/goethite-rich concretion; exact identification requires testing
sedimentary
Chert (Jasper-rich)
Silicon Dioxide (SiO2)
sedimentary
Fossilized Shell
Invertebrate fossil (Bivalvia or Brachiopoda)
fossil
Limestone (Weathered/Silicified)
Sedimentary carbonate rock (primarily CaCO3)
sedimentary
Weathered volcanic rock, likely basalt
Basalt; primarily plagioclase feldspar, pyroxene, and often olivine
igneous
Chert (Polished/Tumbled)
Silicon Dioxide (SiO2)
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartzite Pebble
Metamorphic Quartzite (primarily SiO2)
metamorphic
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, SiO2)
fossil
Quartzite Pebble
Quartzite
metamorphic
Black Obsidian
Volcanic Glass (felsic)
igneous
Jasper (specifically Polychrome or Desert Jasper)
Silicon Dioxide (SiO2) with iron oxide and other mineral impurities
sedimentary (chemical/biological origin)
Weathered porphyritic volcanic rock
Likely andesite or rhyolite porphyry, composed chiefly of feldspar and quartz with iron-oxide staining
igneous
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Mineral
Turritella Agate / Fossiliferous Limestone
Elimia tenera in Chalcedony/Calcite Matrix
fossil
Pink Quartzite Pebble
Quartzite (SiO2)
metamorphic
Chert (Yellow Jasper/Flint)
Silicon dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Orange Quartzite (River Pebble)
Quartzite (SiO2 with iron oxide inclusions)
metamorphic
Fossiliferous Limestone
Fossiliferous Carbonate Rock (CaCO3)
sedimentary
Weathered sandstone
Quartz-rich sandstone (clastic sedimentary rock)
sedimentary
Chert (Field Stone)
Silicon Dioxide (SiO2)
sedimentary
Chert (and Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Quartzite variety)
Microcrystalline Silica (SiO2)
sedimentary
Chert (and its variety Flint)
Silicon dioxide (SiO2) / Microcrystalline quartz
sedimentary
Chert (and Flint variant)
Chert (SiO2)
sedimentary
Chert (Flint nodule)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary