Sedimentary (Chemically Precipitated)

Chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly weathered chert

Jasper

Silicon Dioxide (SiO2), Microcrystalline Quartz

Quartz Geode with Chalcedony

Silicon Dioxide (SiO2)

Quartz Geode (Unbroken)

Silicon Dioxide (SiO2)

Green Jasper / Chert Pebbles

Microcrystalline Quartz (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Chert / Chalcedony Nodules

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Yellow calcite fragment

Calcite (CaCO₃), likely honey/yellow calcite

Blue calcite (probable)

Calcite, calcium carbonate (CaCO₃)

Coquina Limestone (Fossiliferous Limestone)

Calcareous bioclastic sedimentary rock (CaCO3)

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Hematite

Iron(III) oxide (Fe2O3)

Chalcedony (specifically Agate or Flint)

Silicon Dioxide (SiO₂)

Orange Calcite

Calcium Carbonate (CaCO3)

Barite Rose on Marcasite

Barium Sulfate (BaSO4) on Iron Sulfide (FeS2)

Banded iron formation pebble (likely jasper-rich ironstone)

Banded iron formation (BIF), composed mainly of hematite/magnetite and microcrystalline quartz (chert/jasper)

Limestone

Calcium Carbonate (CaCO3)

Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Honey calcite crystal

Calcite (calcium carbonate, CaCO₃)

Banded iron formation (ironstone)

BIF; hematite–magnetite–quartz/chert assemblage

Agate

Agate (Silicon Dioxide - SiO2)

Gneiss with Quartz Veining

Gneiss (High-grade Metamorphic Rock)

Green Calcite

Calcium Carbonate (CaCO3)

Pyrite-bearing Rock / Pyrite Ore

Iron Sulfide (FeS2) in host rock matrix

Yellow Calcite

Calcium Carbonate (CaCO3)

Rough Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Orange Calcite

Calcite (Calcium Carbonate, CaCO3)

Quartz vein in host rock

Quartz (SiO₂), likely in a weathered carbonate or sedimentary matrix

Tufa (Calcareous Tufa)

Calcareous Tufa (Precipitated CaCO3)

Honey-brown calcite crystal cluster

Calcite (CaCO₃), likely dogtooth or scalenohedral calcite

Banded iron formation (ironstone), possibly hematite–magnetite-rich

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and chert/microcrystalline quartz (SiO₂)

Banded iron formation fragment (polished ironstone)

Banded iron formation; hematite/magnetite-rich chert, commonly approximated as Fe₂O₃–Fe₃O₄ with SiO₂

Banded iron formation fragment (likely hematite–magnetite-rich ironstone)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica/chert (SiO₂)

Sulfur

Sulfur (S8)

Blue Calcite

Calcium Carbonate (CaCO3)

Blue calcite

Calcite (CaCO₃), blue variety

Jasper

Silicon dioxide (SiO2) with iron impurities

Iron-rich jasper or ferruginous chert

Microcrystalline quartz (SiO₂) stained by iron oxides, chiefly hematite and goethite

Banded chert pebble

Chert (microcrystalline quartz, SiO₂), likely ribbon-banded chert

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Banded Sandstone (Liesegang Rings)

Sedimentary Arenite (SiO2 with FeO/Fe2O3 impurities)