Limonite-pseudomorph after Pyrite (Prophecy Stone)
Goethite and Limonite secondary minerals (FeO(OH)·nH2O) replacing Pyrite (FeS2)
mineral
Category
Sedimentary (Biogenic)
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Red Quartz (Carnelian/Red Jasper Agate)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
mineral
Calcite
Calcium Carbonate (CaCO3)
mineral
River Stone (Basalt or Siltstone with banding)
Polished Basaltic or Siliciclastic River Cobble
igneous or sedimentary
Pyrite
Iron Disulfide (FeS2)
mineral
Bituminous Coal
Organic Sedimentary Rock (composed mostly of carbon with sulfur and hydrogen)
sedimentary
Sandstone with Liesegang Rings
Clastic Sedimentary Rock with Iron Oxide Precipitates (SiO2 + Fe2O3)
sedimentary
Red Sandstone
Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)
sedimentary
Ferruginous Sandstone (Ironstone)
Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Red Sandstone (Iron-rich Sandstone)
Clastic Sedimentary Rock - Quartz Arenite / Arkose with Hematite Cement
sedimentary
Ferruginous Sandstone
Clastic sedimentary rock (primarily Quartz with Iron Oxide cement)
sedimentary
Sandstone Pebble
Arenite (SiO2 primarily)
sedimentary
Chert (Flint)
Chert (Silicon Dioxide, SiO2)
sedimentary
Sandstone (Ferruginous)
Arenite (Fe2O3 dominant staining)
sedimentary
Chert (Black Chert/Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (specifically tan/pink variety)
Silicon Dioxide (SiO2)
sedimentary
Coal (Bituminous)
Bituminous Coal (C)
sedimentary
Red Sandstone
Arenite (high iron oxide content)
sedimentary
Chert (with Manganese Dendrites)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Red Sandstone
Arenite (composed primarily of Quartz and Iron Oxide)
sedimentary
Chert (Chert / Flint)
Silicon dioxide (SiO2) - Microcrystalline quartz
sedimentary
Red Sandstone (Iron-rich)
Ferruginous Sandstone (variable formula, primarily SiO2 + Fe2O3)
sedimentary
Chert (and Chert-based Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Sedimentary
Petrified Wood
Silicified Wood (SiO2 permineralization)
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Chert (Nodule)
Chert (Silica, SiO2)
sedimentary
Pyrite in Shale
Iron Sulfide (FeS2) in Argillaceous Shale
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Fancy Jasper
Silicon Dioxide (SiO2) with mineral inclusions
sedimentary
Red Sandstone Pebble
Arenite with Hematite (Fe2O3) cement
sedimentary
Jasper (likely Kambaba or Crocodile Jasper variety)
Silicon Dioxide (SiO2) with inclusions
sedimentary
Chert (Mookaite Jasper style)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (with Iron Staining)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (specifically Flint or Jasper variant)
Microcrystalline quartz (SiO2)
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Red Sandstone
Arenite (predominantly SiO2 with Fe2O3)
sedimentary
Chert (Jasper-bearing)
Chert (Silicon Dioxide, SiO2)
sedimentary
Chert (Flint variety)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Pyritic Mudstone
Argillaceous rock (FeS2)
sedimentary