Sedimentary (Chemically Precipitated)

Golden Calcite

Calcium Carbonate (CaCO3)

Calcite

Calcium Carbonate (CaCO3)

Pyrite

Iron Sulfide (FeS2)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Orange Calcite

Calcium Carbonate (CaCO3)

Green Calcite

Calcium Carbonate (CaCO3)

Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Blue calcite (probable)

Calcite — CaCO₃

Weathered flint (chert) pebble

Microcrystalline quartz, SiO₂ (flint/chert)

Sandstone with Concretions / Liesegang Rings

Arenite with iron oxide banding

Vein Quartz in Host Rock

Silicon Dioxide (SiO2) vein in sedimentary/metamorphic matrix

Quartz Vein Specimen

Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Banded iron formation fragment

Banded iron formation (BIF), chiefly hematite/magnetite and chert (SiO₂)

Limonite (Ironstone)

Hydrated Iron(III) Oxide-hydroxide (FeO(OH)·nH2O)

Chert / Flint (with Crinoid Stem Molds)

Microcrystalline Quartz (SiO2)

Dyed Quartz Geode

Silicon Dioxide (SiO2) with artificial pigment

Banded Iron Formation (BIF) / Ironstone Conglomerate

Ironstone (Hematite/Goethite rich sedimentary rock)

Banded iron formation (ironstone)

Banded iron formation; chiefly hematite/magnetite (Fe₂O₃/Fe₃O₄) with chert (SiO₂)

Amethyst Geode

Amethyst/Purple Quartz (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Honey Calcite

Calcite (Calcium Carbonate, CaCO3)

Hematite

Iron(III) oxide (Fe2O3)

Sandstone Cobble with Liesegang Rings

Arenite with iron oxide precipitation (SiO2 matrix with Fe2O3 banding)

Banded iron formation fragment (ironstone)

Banded iron formation; chiefly hematite/magnetite with chert (SiO₂)

Weathered limestone pebble

Limestone; predominantly calcite (CaCO₃)

Fossiliferous Limestone

Calcite (CaCO3) matrix with biogenic fragments

Green Jasper

Microcrystalline Quartz (SiO2)

Moqui Marble

Ironstone Concretion (Goethite/Hematite)

Sandstone with Manganese Dendrites

Arenite (mostly SiO2) with Manganese Oxide inclusions (MnO2)

Orange calcite

Calcite (calcium carbonate, CaCO₃)

Weathered iron-rich rock, possibly limonite-bearing sandstone

Limonite/goethite-bearing sandstone or ferruginous conglomeratic rock

Milky Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Calcite crystal cluster

Calcite — calcium carbonate, CaCO₃

Likely ironstone concretion

Iron-oxide-cemented sedimentary concretion, commonly hematite/goethite-rich

Pink calcite cluster

Calcite (calcium carbonate, CaCO₃)

Goldstone

Man-made glass infused with copper crystals

Quartz Geode / Druzy Quartz

Silicon Dioxide (SiO2)

Red Jasper

Silicon Dioxide with Iron Oxide (SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

White quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂); possibly quartzite, a metamorphosed quartz sandstone