Limonite (Ironstone)
Limonite (FeO(OH)·nH2O)
mineral
Category
Mineral (Silicate Replaced Organic Material)
Browse mineral (silicate replaced organic material) specimens identified by the Rock Identifier community.
Limestone (Concretionary or Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (likely River-tumbled Picture Sandstone)
Arenite (predominantly SiO2 with iron oxide impurities)
sedimentary
Sandstone (with Lichen)
Arenite (primarily SiO2)
sedimentary
Chert (variations include Flint/Jasper)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chrysocolla
Hydrated copper phyllosilicate mineral (Cu,Al)2H2Si2O5(OH)4·n(H2O)
mineral
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
mineral
Pyrite on Limestone
Iron Disulfide (FeS2) in Calcium Carbonate (CaCO3) matrix
sedimentary (matrix) / mineral (inclusion)
Fossilized Crinoid Stem Segment
Crinoid (Phylum Echinodermata, Class Crinoidea)
sedimentary
Jasper with Manganese Dendrites
Silicon Dioxide (SiO2) with Oxide Mineral Inclusions
sedimentary
Chert (or Flint)
Chert (Sedimentary Cryptocrystalline Sio2)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Amber
Succinicum (Organic polymer, largely C10H16O)
Organic Mineral
Moss Agate
Chalcedony (Silicon Dioxide with inclusions) - SiO2
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Marble
Recrystallized Calcite (CaCO3)
metamorphic
Milky Quartz (or Bull Quartz)
Silicon Dioxide (SiO2)
mineral
Silver (Morgan Dollar)
Native Silver (Ag) - 90% Silver, 10% Copper alloy
mineral
Amazonite
K(AlSi3O8), Microcline (potassium feldspar)
mineral
Amber
Succinite (fossilized resin, C10H16O)
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Fuchsite
Chromium-rich Muscovite (KAl2(AlSi3O10)(OH,F)2 with Cr replacements)
mineral
Chert (specifically Banded Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Septarian Nodule or Mud Crack Fossil
Septarian Nodule (Concretion)
sedimentary
Sandstone (likely Arkosic or Lithic Sandstone)
Clastic Sedimentary Rock (SiO2 with assorted minerals)
sedimentary
Limonite (Iron-rich Siltstone / Sandstone base)
Hydrous ferric oxide mixture (FeO(OH)·nH2O)
sedimentary
Sandstone
Arenite
sedimentary
Mica Schist
Mica Schist (primarily Muscovite or Biotite sheet silicates)
metamorphic
Precious Red Coral
Corallium rubrum / Corallium japonicum
mineral (organic gemstone)
Ocean Jasper Mushroom
Orbicular Jasper (Silicon Dioxide, SiO2 mixed with various impurities)
mineral
Chert (specifically Tan Chert)
Chert (SiO2)
sedimentary
Snowflake Obsidian
Obsidian with Cristobalite inclusions (Amorphous SiO2 + SiO2 inclusions)
igneous
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
igneous
Caliche (with Lichen Cover)
Calcium carbonate-cemented soil layer (CaCO3)
sedimentary
Quartz (Microcrystalline/Chert)
Silicon Dioxide (SiO2)
mineral
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily Quartz with Limonite/Goethite staining)
sedimentary
Sandstone
Arenite (variable SiO2 composition)
sedimentary
Chert (Iron-stained)
Microcrystalline silica (SiO2) with trace Iron oxide (Fe2O3)
sedimentary
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Emerald in Schist (Raw/Tumbled)
Beryllium Aluminum Silicate (Be3Al2Si6O18) with Chromium/Vanadium impurities in Mica Schist
metamorphic
Jasper (Picture Jasper variety)
Silicon Dioxide (SiO2) with impurities
sedimentary
Garnetiferous Pegmatite
Pegmatite with Almandine Garnet and Muscovite
igneous