Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (70% or more silicon dioxide)
Category
Browse organic (non rock) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (70% or more silicon dioxide)
Green glass sphere/marble
Soda-lime glass (primarily SiO2, Na2O, CaO)
Crushed Limestone
Sedimentary Calcium Carbonate (CaCO3)
Drill Core Sample
Cylindrical Rock Core (Specific mineralogy varies by extraction site)
N/A - Non-Geological Item
Obsidian
Volcanic Glass (felsic composition)
Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxides
Quartzite
Quartzite
Chert (Jasper variation)
Microcrystalline Quartz (SiO2)
Chert (Commonly called Jasper or Flint)
Chert (SiO2)
Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
Ferruginous Sandstone (Ironstone)
Arenite with Iron-Oxide Cement (FeO(OH)·nH2O / Fe2O3)
Green Opal (Prase Opal)
SiO2 · nH2O (Hydrated Silicon Dioxide)
Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
Quartzite (River Cobble)
Quartzite (predominantly SiO2)
Limestone
Sedimentary rock composed mainly of calcite (CaCO3)
Shale
Fissile Clay-dominant Mudrock (SiO2, Al2O3, K2O, Na2O, CaO, MgO)
Glauconitic Sandstone
Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
Fossiliferous Limestone
Calcite-rich Fossiliferous Limestone (CaCO3)
Fossil Coral (Rugose Coral Fragment)
Rugosa (extinct order of solitary and colonial corals)
Dinosaur Fossil Tooth
Vertebrate Fossilized Tooth
Chert / River Pebble
Silicon Dioxide (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Fossiliferous Limestone (Coquina / Shell Limestone)
Biogenic Limestone (Calcium Carbonate, CaCO3)
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
Flower Jasper
Agatized Fossil Coral / Chalcedony (SiO2)
Chert (Jasper/Mudstone variety with Oxidation)
Silicon dioxide (SiO2)
Shale (possibly Carbonaceous or Oil Shale)
Argillaceous Sedimentary Rock
Coquina / Shelly Sandstone
Calcareous Sandstone / Coquina
Agate (Moss or Dendritic Agate)
Chalcedony (Silicon Dioxide, SiO2)
Anthracite Coal
Anthracite (a variety of coal, predominantly carbon)
Quartz-rich rock, likely milky quartz vein material
Quartz (SiO₂), possibly iron-stained massive quartz with minor feldspar or mica
Quartzite
Quartzite (Primary mineral: Silicon Dioxide, SiO₂)
Obsidian
Obsidian (Volcanic Glass)
Shale with Vein Infillings
Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.
Chert (Nodule)
Silicon Dioxide (SiO2)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Quartzite Pebble (River Rock)
Metamorphic Quartzite (predominantly SiO2)
Quartzite River Rock
Metamorphosed Sandstone (SiO2)
Quartzite River Rock
Quartzite (primarily SiO2)
Tufa Rock and Tumbled Gemstones
Calcareous Tufa (Calcium Carbonate, CaCO3)
Snowflake Obsidian
Obsidian with Spherulitic Cristobalite (SiO2)