Sedimentary (Biogenic Sediment Or Biological Remain)

Orange Calcite

Calcium Carbonate (CaCO3)

Red Jasper

Silicon Dioxide with Iron Oxide impurities (SiO2 + Fe2O3)

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Chert (often colloquially called Flint)

Chert (Microcrystalline Quartz, SiO2)

Slate

Foliated Metamorphic Rock (primarily composed of quartz, illite, and chlorite)

Jasper (specifically Oolitic or Brecciated Jasper)

Silicon Dioxide (SiO₂)

Marble

Recrystallized Limestone (CaCO3)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Mica Schist

Muscovite Schist (KAl2(AlSi3O10)(OH)2)

Carnelian Agate

Chalcedony (SiO2 with Iron Oxide impurities)

Chert (Yellow Jasper)

Silicon Dioxide (SiO2)

Limonite Pseudomorph after Pyrite

Limonite (Hydrous iron oxides e.g., FeO(OH)·nH2O) pseudomorphing Pyrite (FeS2)

Sandstone (likely Quartzose)

Clastic sedimentary rock (SiO2 primary)

Limonite Concretion (Ironstone)

Limonite (Hydrated Iron(III) Oxide-Hydroxide, FeO(OH)·nH2O)

Hematite

Iron(III) oxide (Fe2O3)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Ferruginous Sandstone

Arenite with Hematite/Limonite cement

Citrine Geode

Citrine (Silicon Dioxide, SiO2)

Rhodonite

Manganese Silicate (Mn,Fe,Mg,Ca)SiO3

Chalcedony

Cryptocrystalline Quartz (SiO2)

Jasper (Cream/Yellow variety)

Jasper (Microcrystalline Quartz, SiO2)

Specular Hematite

Iron Oxide (Fe2O3)

Green Common Opal

Hydrated Silica (SiO2·nH2O)

Jasper (Liver Jasper or Chocolate Jasper)

Jasper (Silicate - SiO2)

Magnetite

Magnetite (Fe3O4)

Banded Agate

Agate (Cryptocrystalline Quartz, SiO2)

Quartz (Milky/Gray variety)

Silicon Dioxide (SiO2)

Ferruginous Sandstone (Ironstone)

Sedimentary rock with Limonite/Goethite cement

Jasper with Quartz inclusions

Silicon Dioxide (SiO2)

Red Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Unakite

Epidotized Granite

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (primarily SiO2)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Limonite (Ironstone)

Limonite (FeO(OH)·nH2O)

Limonite (Iron Ore)

Limonite (Hydrous iron(III) oxide-hydroxide mixture, primarily FeO(OH)·nH2O)