Corundum (Sapphire/Ruby in Matrix)
Aluminium oxide (Al2O3)
Category
Browse sedimentary (if natural jasper) or artificial (if slag) specimens identified by the Rock Identifier community.
Corundum (Sapphire/Ruby in Matrix)
Aluminium oxide (Al2O3)
Conglomerate
Conglomerate (Detrital Sedimentary Rock)
Natural or Cultured Pearl
Calcium Carbonate (Aragonite and Conchiolin), CaCO3
Pyrite
Iron Sulfide (FeS2)
Ironstone Nodules / Siderite Concretion
Siderite (FeCO3) / Ferruginous Septarian Concretion
Chalcedony (River Stone)
Microcrystalline Quartz (SiO2)
Ferruginous Sandstone with Ironstone Concretion
Goethite-rich Sandstone (FeO(OH))
Chert (often called Flint or Agate nodule)
Cryptocrystalline Quartz (SiO2)
Red Sandstone
Arenite (with Iron Oxide / Hematite), Formula: SiO2 (Quartz) + Fe2O3 (Hematite coating)
Coral Fossil (Favosites)
Favosites (Extinct genus of tabulate corals)
Conglomerate
Conglomerate (a clastic sedimentary rock)
Agate
Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony
Calcite
Calcium Carbonate (CaCO3)
Almandine Garnet
Iron aluminum silicate - Fe3Al2(SiO4)3
Pink Tumbled Agate (Dyed)
Silicon Dioxide (SiO2) with artificial dyes
Sandstone with Quartz Veins
Arenite (primarily SiO2 with Fe2O3 staining)
Red Siltstone
Siltstone (composed mainly of SiO2 and Fe2O3)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Yellow Calcite
Calcium Carbonate (CaCO3)
Siltstone
Siltstone (primarily composed of SiO2, Al2O3, and phyllosilicates)
Garnet Schist
Garnetiferous Mica Schist
Orpiment
Orpiment (As2S3)
Chert (often referred to as Flint)
Chert (Microcrystalline or cryptocrystalline Quartz, SiO2)
Quartz Geode in Sedimentary Matrix
Silicon Dioxide (SiO2) within a limestone/dolostone host
Calcite (or Alabaster, if truly carved)
Calcium Carbonate (CaCO3)
Fossilized Brachiopod
Phylum Brachiopoda (General mineral composition: Calcite/CaCO₃ or Silica/SiO₂)
N/A - Man-made object (Jewelry Chain)
Antiqued or Oxidized Metal Chain (often Steel or Brass)
Pebble (Likely Basalt or Siltstone)
Clastic sedimentary rock or mafic volcanic rock
Chert Pebble with Quartz Veins
Microcrystalline Quartz (SiO2)
Chert (Common Variety)
Cryptocrystalline Quartz (SiO2)
Optical Calcite (Iceland Spar)
Calcium Carbonate (CaCO3)
Druzy Quartz (on Chalcedony/Agate base)
Silicon Dioxide (SiO2)
Banded Sandstone (Quartzite-rich)
Clastic Sedimentary Rock (SiO2 with Iron Oxide impurities)
Limestone
CaCO3 (principally Calcite)
Chert (specifically Flint)
Chert (SiO2)
Agate Geode
Silicon Dioxide (SiO2) - variety Chalcedony/Quartz
Hematite with Magnetite
Iron Oxide (Fe2O3)
Quartz (Milky or Cloudy variety)
Silicon Dioxide (SiO2)
Sandstone (Muddy/Silty Variety)
Arenite with high silt/clay content (clastic sedimentary rock)
Coquina or Fossiliferous Limestone
Fossiliferous Calcarenite (CaCO3)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Dyed Agate
Chalcedony (Silicon Dioxide, SiO2)