Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with inclusions
mineral
Category
Organic (Non Geological)
Browse organic (non geological) specimens identified by the Rock Identifier community.
Glauconitic Sandstone
Glauconitic Quartz Arenite
sedimentary
Limestone (with weathering rind)
Calcium Carbonate (CaCO3)
sedimentary
Dark metamorphic rock, likely biotite schist or gneiss
Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing
metamorphic
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
mineral
Glendonite (Calcite Pseudomorph after Ikaite)
Calcite (CaCO3) pseudomorph after Ikaite (CaCO3·6H2O)
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Siltstone
Siltstone
sedimentary
Sandstone
Arenite (SiO2 composed primarily of quartz)
sedimentary
Baltic Amber (Butterscotch variety)
Succinite
Organic Gemstone/Mineraloid
Septarian Nodule (Micro-fragment)
Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
metamorphic
Obsidian
Obsidian (Volcanic Glass)
Igneous
Black Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Quartzite with Iron Oxide Vein
Metamorphic Quartzite (SiO2 with Hematite/Limonite impurities)
metamorphic
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Glauconitic Sandstone (Greensand)
Glauconitic quartz wacke or arenite
sedimentary
Slag Glass (Cullet Glass)
Amorphous Silica (Industrial byproduct)
mineral
Common Opal (Green Opal / Pistachio Opal)
Hydrated silica (SiO2·nH2O)
mineraloid
River Pebble (Greywacke or Quartzite-rich Sandstone)
Lithic Sandstone (primarily SiO2 with rock fragments)
sedimentary
Black obsidian (probable)
Volcanic glass; primarily SiO₂-rich rhyolitic composition
igneous
Black Obsidian
Obsidian (Volcanic Glass)
igneous
Fossilized Fish Skeleton in Matrix
Vertebrata (Class: Actinopterygii), typically found in limestone or shale matrices
sedimentary
Geode with Quartz Crystal Cavity
Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix
sedimentary
Gastropod Steinkern (Fossil Snail Internal Mold)
Class Gastropoda (Internal Mold)
sedimentary
Quartzite
Metamorphic Quartzite (primarily SiO2)
metamorphic
Fossilized Brachiopod
Brachiopoda (e.g., Atrypa or Rhynchonellida)
fossil
Obsidian with Spherulitic Devitrification (Snowflake Obsidian/Mahogany related)
Volcanic Glass (70% or more SiO2)
igneous
Pyrite in Slate
Iron Sulfide (FeS2) in Slate host matrix
metamorphic
Obsidian
Obsidian (Amorphous volcanic glass)
igneous
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Chert (Pink Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert Nodule (Flint)
Silicon Dioxide (SiO2)
sedimentary
Ironstone Concretion / Limonite Node
Goethite and Limonite (FeO(OH) nH2O)
sedimentary
Banded Chert with Quartz Veining
Microcrystalline Quartz (SiO2)
sedimentary
Chert (varieties: Flint or Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian (worked into an arrowhead profile)
Obsidian (volcanic glass), primarily SiO2 (Silicon Dioxide)
igneous
Red cabochon gemstone, likely carnelian or dyed chalcedony
Chalcedony (microcrystalline quartz), SiO₂; exact identification requires testing
gemstone