Garnet (Almandine variety)
Almandine, Fe3Al2(SiO4)3
Category
Browse organic (non geological) specimens identified by the Rock Identifier community.
Garnet (Almandine variety)
Almandine, Fe3Al2(SiO4)3
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide)
Chert (variations include Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Iron Ore / Hematite / Ironstone Nodule
Hematite / Goethite (Fe2O3 / FeO(OH))
Red Jasper
Red Jasper (variety of Chalcedony, SiO₂)
Chert (Flint)
Chert (Cryptocrystalline variety of Quartz, SiO2)
Quartzite
Metamorphosed Quartz Sandstone (SiO2)
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
Obsidian
Volcanic glass (no mineral formula due to amorphous structure, mostly SiO2)
Banded Sedimentary Rock (Siltstone/Mudstone with concretion)
Siltstone with Ferruginous Banding
Jasper
Silicon Dioxide (SiO2) with iron oxide impurities
Chert (variations include Flint or Jasper)
Silicon Dioxide (SiO2)
Chert (Jasper variation)
Chert (SiO2)
Fossil Coral
Phylum Cnidaria / Rugosa or Tabulata
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Petrified Wood
Silicified Wood (SiO2)
Sandstone
Sandstone (clastic sedimentary rock, composed predominantly of sand-sized minerals or rock fragments)
Petrified Wood
Silicified Wood (SiO2)
Fossiliferous Limestone with Rugose Coral
Calcium Carbonate (CaCO3) featuring Rugosa (extinct order of solitary and colony corals)
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite/Magnetite inclusions
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (70% or more silicon dioxide)
Chert Nodule
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (primarily SiO2)
Petrified Wood
Silicified Wood (primarily SiO₂ / Silicon Dioxide)
Obsidian
Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)
Ironstone Concretion / Goethite-Hematite Geode
Goethite / Hematite Concretion (Fe3O4 / FeO(OH) / Fe2O3)
Petrified Wood
Silicified Wood (SiO2)
Chert Nodule in Limestone (Flint in Chalk)
SiO2 (Microcrystalline Quartz) in CaCO3 (Calcite)
Coal (most likely Bituminous or Anthracite)
Coal (organic sedimentary rock)
Fossilized coral (likely honeycomb or branching coral)
Fossil coral; probable Scleractinia or Tabulata, composition mainly microcrystalline CaCO₃
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
Petrified Wood (Silicified Wood)
Silicified Wood / Silicon Dioxide (SiO2)
Chert Nodule
Chert (Microcrystalline Silicon Dioxide, SiO2)
Green Moss Agate
Agate (Silicon Dioxide - SiO2) with inclusions of hornblende or chlorite
Chert (specifically a fragment with Desert Varnish)
Microcrystalline quartz (SiO2)
Opalite (a synthetic glass)
Silicon Dioxide (SiO2) with various additives; not a true mineral but a man-made gem simulant
Quartz Vein in Schist
Quartz (SiO2) in Mica Schist
Fossiliferous Limestone
Sedimentary rock containing Indeterminate Fossil remains (likely Crinoid stem or Bryozoan fragment)
Fossiliferous Siltstone
Clastic Sedimentary Rock with Fossil Inclusions
Septarian Nodule or Mud Crack Fossil
Septarian Nodule (Concretion)
Quartzite
Quartzite (Metamorphic Quartz Arenite)
Chert (Flint)
Microcrystalline Quartz (SiO2)