Fossiliferous Limestone
Calcite-rich Sedimentary Rock (CaCO3)
sedimentary
Category
Organic (Non Geological)
Browse organic (non geological) specimens identified by the Rock Identifier community.
Ironstone Concretion (Iron-rich Mudstone)
Siderite / Geothite concretion (FeCO3 / FeO(OH))
sedimentary
Ironstone Concretion
Siderite or Hematite Concretion
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Ironstone Concretion
Siderite or Goethite Concretion
sedimentary
Obsidian (specifically Silver Sheen Obsidian)
Volcanic Glass (approx. 70–75% SiO2 plus MgO, Fe3O4)
igneous
Red Sandstone
Arenite (Iron-rich Sandstone)
sedimentary
Travertine
Calcareous Tufa (CaCO3)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)
metamorphic
Septarian Nodule (Dragon Stone)
Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)
sedimentary
Petrified Wood
Silicified wood (Quartz/Chalcedony - SiO2)
sedimentary
Travertine (Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Travertine (often colloquially called Tufa)
Chemical Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Jasper
Agate/Jasper (Microcrystalline Quartz, SiO2)
sedimentary
Banded Chert
Microcrystalline silicon dioxide (SiO2)
sedimentary
Water and Silt (Sedimentary Environment)
Suspended Sediment / H2O (dihydrogen monoxide)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
mineral
Obsidian
Volcanic Glass (Amorphous Silica)
igneous
Fossilized Gastropod (Snail)
Class Gastropoda (internal mold or 'steinkern')
sedimentary
Quartz (likely) or a Quartzite Pebble
Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.
Mineral, specifically a detrital grain
Jasper
Silicon Dioxide (Microcrystalline Quartz / Chalcedony)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Sandstone Pebble (River Rock)
Sandstone (Quartz-rich sedimentary rock with iron oxide staining)
sedimentary
Black Marble with Quartz Veining
Metamorphosed Limestone (Recrystallized CaCO3)
metamorphic
Red Sandstone with Reduction Spot
Quartzose Sandstone with a Leach/Reduction Spot
sedimentary
Sandstone (with carbonaceous plant fragments)
Arenite (composed primarily of SiO2)
sedimentary
Green Moss Agate
Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
Mineral (Variety of Chalcedony)
Anthracite Coal
Anthracite (a variety of coal, predominantly carbon)
Sedimentary Rock (Metamorphosed)
Hardpan Nodule / Ferruginous Sandstone
Ferruginous Sandstone (Fe-cemented sediment)
sedimentary
Chert with Calcite Veining
Microcrystalline Quartz (SiO2) with Calcium Carbonate (CaCO3) veins
sedimentary
Peridot
Olivine ((Mg,Fe)2SiO4)
Mineral
Pyrite
Iron Pyrite (FeS2)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Black Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Basaltic Tuff / Volcanic Breccia
Pyroclastic Breccia / Lithic Tuff
igneous
Golden Sheen Obsidian
Obsidian (volcanic glass) with inclusions of gas bubbles and mineral crystals (e.g., hematite, magnetite) causing the sheen
igneous
Feldspar-rich Quartzite
Feldspathic Quartzite (Metamorphosed Sandstone)
Metamorphic
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Ambergris (Marine Coprolite/Subfossil)
Marine organic coprolite / Ambergris (Physeter macrocephalus metabolite)
fossil
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Sandstone with Trace Fossils
Quartz Arenite with Bioturbation (Trace Fossils)
sedimentary