Sedimentary (Chemical)

Limonite Pseudomorph after Pyrite

Limonite (Hydrous iron oxides, FeO(OH)·nH2O) replacing Pyrite (FeS2)

Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Quartz (Milky or Cloudy Quartz)

Silicon Dioxide (SiO2)

Chert (with Quartz veins)

Microcrystalline quartz (SiO2)

Chert (Golden/Yellow Variety)

Microcrystalline Silica (SiO2)

Chert (containing Flint and Chalcedony)

Microcrystalline Quartz (SiO2)

Chert (specifically Tan/Brown Chert)

Chert (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Slate

Slate (Foliated Metamorphic Rock)

Agate (Chalcedony)

Cryptocrystalline Silica or Silicon Dioxide (SiO2)

Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')

Calcite (Calcium Carbonate, CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Chert (specifically Jasper or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Limonite (after Pyrite Pseudomorph)

Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)

Limestone (Cliff Formation)

Limestone (predominantly CaCO3 as calcite)

Quartz (Grain/Fragment)

Silicon Dioxide (SiO2)

Chert Nodule (Commonly known as a Flint or River Cobble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Ferruginous Quartz (Carnelian-tinted Quartz)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Chert (Chert Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Iron-stained River Cobble)

Microcrystalline Quartz (SiO2)

Marble

Metamorphosed Limestone (main mineral: Calcite, CaCO3)

River Stone (likely Basalt or Chert)

Silicon Dioxide (SiO2) for chert or Mafic Extrusive Rock for basalt

Granite (phaneritic background) with Limestone/Calcite carving

Felsic Igneous Plutonic Rock (background) / Calcium Carbonate (CaCO3) (carving)

Quartzite (River Cobble)

Quartzite (primarily SiO2)

Quartz Pebble (Milky and Gray)

Quartz (Silicon Dioxide, SiO2)

Limonite Pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O replacing Pyrite FeS2

Chert (often called Flint when dark or found in chalk)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint nodule)

Silicon dioxide (SiO2)

Mookaite Jasper

Silicified Radiolarite (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Septarian Nodule

Septarian Concretion

Chert Pebble with Quartz Veins

Microcrystalline Quartz (SiO2)

Gray Quartz (Tumbled)

Silicon Dioxide (SiO2)

Graphite

Graphite (Native Carbon, C)

Quartz Pebble (Chalcedony/Agate variety)

Silicon Dioxide (SiO2)

Banded Agate

Chalcedony (Silicon Dioxide, SiO2)

Limestone

Calcium Carbonate (CaCO3)

Limestone (Micrite/Chalky variety)

Calcium Carbonate (CaCO3)

Pink Dyed Agate (Pink Agate Slice)

Silicon Dioxide (SiO2) - Chalcedony / Cryptocrystalline Quartz

Rock Salt / Halite Crust

Halite (Sodium Chloride, NaCl)

Coquina

Biogenic Limestone (Calcium Carbonate - CaCO3)