Shale
Fissile mudstone (primarily clay minerals and silt-sized quartz)
Category
Browse organic (non rock) specimens identified by the Rock Identifier community.
Shale
Fissile mudstone (primarily clay minerals and silt-sized quartz)
Chert (Yellow/Tan)
Microcrystalline Quartz (SiO2)
Stromatolite
Biogenic Sedimentary Rock (composed predominantly of CaCO3)
Pyrite in Shale
Iron Disulfide (FeS2) in Argillaceous Shale
Chert (specifically Flint or Gray Chalcedony)
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Obsidian
Volcanic glass (SiO2-rich extrusive igneous rock)
Chert (Nodule)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Chert (Iron-stained)
Chert (Silicon Dioxide, SiO2)
Sandstone Concretion
Clastic sedimentary rock (primarily Quartz SiO2)
Fossiliferous Limestone
Calcite-rich Sedimentary Rock (CaCO3)
Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Iron-Stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
N/A (Non-Geological Specimen)
Green Chert (Jasper)
Silicon Dioxide (SiO2)
Chert (Brecciated River Cobble)
Silicon Dioxide (SiO2)
Tufa (Limestone)
Calcareous Tufa (CaCO3)
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Chert (Field Stone)
Chert (SiO2)
Tree Agate
Dendritic Agate (Silicon Dioxide, SiO2)
Chert (Jasper/Mudstone)
Silicon Dioxide (SiO2)
Chert (Chert Pebble)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert (White-Tan variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Flint)
Chert (SiO2)
Quartzite
Quartzite (Primary mineral: SiO2)
Chert (Iron-stained)
Chert (SiO2)
Fossiliferous Limestone (Coquina / Shell Limestone)
Biogenic Limestone (CaCO3)
Fossil Coral (Honeycomb Coral)
Favosites (extinct genus of Tabulate coral)
Quartzite River Rock (with Limonite staining)
Quartzite (SiO2)
Chert (Tan/Yellow variety)
Microcrystalline quartz (SiO2)
Chert (or Flint)
Chert (Sedimentary Cryptocrystalline Sio2)
Chert (specifically Flint or Jasper variant)
Cryptocrystalline Quartz (SiO2)
Ferruginous Sandstone (Ironstone)
Sedimentary rock with Limonite/Goethite cement
Limestone
Calcium Carbonate (CaCO3)
Yellow Chert (Jasper)
Microcrystalline Quartz (SiO2)
Amber
Succinite (Fossilized Tree Resin)
Coal (Anthracite)
Anthracite (Carbon-based organic sedimentary/metamorphic rock)
Rough Dark Green Sapphire
Corundum (Al2O3)
Druzy Quartz on Vesicular Basalt
Silicon Dioxide (SiO2) in an extrusive Mafic igneous host rock