Limonite (Ironstone Concretion)
Limonite: FeO(OH)·nH2O
Category
Browse organic materia (not a rock or mineral) specimens identified by the Rock Identifier community.
Limonite (Ironstone Concretion)
Limonite: FeO(OH)·nH2O
Chert (varieties include Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz Geode
Silicon Dioxide (SiO2)
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
Sandstone
Sandstone (Sedimentary rock composed of silicate grains)
Greenstone
Protolith: Basaltic rock
Sandstone
Arenite (Sedimentary Rock)
Fossilized bivalve shell in limestone
Calcitic fossil shell; likely an oyster or other rudist/bivalve (Bivalvia), preserved in carbonate rock
Porphyritic Basalt or Lamprophyre
Extrusive igneous rock with visible phenocrysts
Chert (often called Flint in this variation)
Silicon dioxide (SiO2) - Microcrystalline quartz
Chert (Yellow or Tan Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Gneiss
Gneiss (High-grade metamorphic rock)
Gneiss
Gneiss
Tiger Iron
Tiger Iron (Composition: SiO2, Fe2O3, Fe3O4)
Quartz-veined Granite or Gneiss Pebble
Silicate-rich metamorphic rock fragment
Quartz Druzy (Geode Fragment)
Silicon Dioxide (SiO2)
Calcite
Calcium Carbonate (CaCO3)
Chert (Green Chert or Jasper)
Microcrystalline Quartz (SiO2)
Sandstone
Clastic Sedimentary Rock
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Fossil Bivalve / Ostreid Shell (Hag Stone / Perforated Pebble)
Phylum Mollusca, Class Bivalvia
Sandstone with Quartz/Calcite druse
Arenite with druse (SiO2 or CaCO3)
Chert (Chalcedony/Agate)
Microcrystalline Quartz (SiO2)
Hypersthene
Hypersthene ((Mg,Fe)SiO₃)
Granite
Felsic intrusive igneous rock
Quartz
Silicon Dioxide (SiO2)
Sandstone with Dendritic Inclusions
Quartzose Sandstone
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Quartz (Druzy or Chalcedony variant)
Silicon Dioxide (SiO2)
Basalt Pebble
Extrusive Igneous Rock (Mafic)
Quartz Vein in Siltstone
SiO2 (Quartz) on clastic sedimentary matrix
Basalt with Vesicular Amygdule
Extrusive igneous rock (Mafic)
Chert (Yellow Jasper/Flint)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Petrified Wood
Silicified wood (primarily quartz, SiO2)
Slickenside
Tectonic Fault Scarp Surface
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Gneiss
High-grade Metamorphic Gneiss
Unakite
Epidotized Granite
Granite
Intrusive Igneous Rock
Mixed River Pebbles (including Unakite and Jasper)
Polymineralic geological specimens
Eclogite
Eclogite (Omphacite-Garnet rock)
Sandstone (Graywacke)
Clastic Sedimentary Rock (Lithic Sandstone)