Iceland Spar (Optical Calcite)
Calcite (Calcium Carbonate, CaCO3)
Category
Browse sedimentary (with some aspects of mineral replacement) specimens identified by the Rock Identifier community.
Iceland Spar (Optical Calcite)
Calcite (Calcium Carbonate, CaCO3)
Almandine Garnet
Almandine (Fe3Al2(SiO4)3)
Chert (containing Flint and Chalcedony)
Microcrystalline Quartz (SiO2)
Gneiss (specifically Granitic Gneiss)
Gneiss (composed primarily of Quartz, Feldspar, and Biotite/Amphibole)
Magnetite (Lodestone variety)
Magnetite (Iron(II,III) oxide, Fe3O4)
Magnetite (Iron Ore)
Magnetite (Fe3O4)
Galena
Lead Sulfide (PbS)
Gneiss (Metamorphic Cobble)
Gneiss
Chert (Jasper/Agate variety)
Microcrystalline quartz (SiO2)
Sandstone Beach Pebble
Clastic Sandstone (SiO2 - Quartz-dominant)
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
Gneiss
Gneiss (High-grade metamorphic rock)
Sandstone (Stream-rounded Cobble)
Arenite (composed primarily of SiO2, Silica)
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
Pyrite
Iron Sulfide (FeS2)
Fossilized Rugose Coral (Horn Coral)
Order Rugosa (extinct tetra-coral)
Chert (Jasper/Chalcedony)
Microcrystalline Quartz (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Quartz Geode
Silicon Dioxide (SiO₂)
Red Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Ironstone Concretion
Siderite or Hematite-bonded Concretion
Gneiss
Gneiss (High-grade Metamorphic Rock)
Sandstone Concretion
Septarian or Carbonate-cemented Sandstone Concretion
Dinosaur Bone (Gembone)
Petrified Dinosaur Bone (Apatite/Silica replacement)
Sandstone (Ferruginous)
Arenite (primarily SiO2 with iron oxide cement)
Pyrite
Iron Sulfide (FeS2)
Belemnite Fossil (Guard)
Belemnoidea (Carbonate/Calcite replacement)
Siltstone with iron staining
Siltstone (primarily SiO2 with FeO(OH) coatings)
Sandstone
Sandstone (clastic sedimentary rock)
Geode (Quartz)
Silicon Dioxide (SiO2)
Agate (specifically a Blue Agate Geode Slice)
Chalcedony (cryptocrystalline variety of Quartz); SiO2
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
Chert (Common Chert)
Cryptocrystalline Quartz (SiO2)
Agate Geode
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Gneiss with Quartz Vein
Gneiss containing Quartz (SiO2) filler
Gneiss (Granitic Gneiss)
Gneiss (composed primarily of Quartz, Feldspar, and Mica/Amphibole)
Ironstone Concretion (Moqui Marble)
Iron Oxide Concretion (Fe2O3 / FeO(OH) mixed with SiO2)
Red Jasper
Microcrystalline Quartz (SiO2) with Hematite impurities
Chert (specifically Chalcedony/Flint variant)
Silicon Dioxide (SiO2)
Chert / Flint
Cryptocrystalline quartz (SiO2)
Jasper
Jasper (Silicon Dioxide, SiO2)