Sedimentary (Biogenic)

Sandstone (Wonderstone)

Silicified Sandstone / Orthoquartzite with Liesegang rings

Chert (specifically Jasper or Flint variant)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Bloodstone

Heliotrope (cryptocrystalline Quartz, SiO2 with inclusions of Hematite)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Opaque cryptocrystalline variety of Quartz

Chert (Iron-stained)

Chert (Microcrystalline and Cryptocrystalline Quartz, SiO2)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert

Chert (SiO2)

Coral Fossil (Favosites)

Favosites (Calcite/Calcium Carbonate, CaCO3)

Fossilized Gastropod in Chert/Limestone

Internal mold of Gastropoda (Class) with CaCO3 or SiO2 mineral formula

Sandstone

Arenite (SiO2 predominantly)

Jasper with Iron Inclusions

Silicon Dioxide (SiO2) with impure Iron Oxides

Chert (containing Calcite or Quartz inclusions)

Silicon Dioxide (SiO2) with varying mineral impurities

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (Jasper variety)

Microcrystalline quartz (SiO2)

Moqui Marble

Ironstone Concretion (Goethite/Hematite)

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Coral Fossil (Petrified Coral)

Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)

Chert Pebble

Microcrystalline Quartz (SiO2)

Crinoid and Coral Fossils in Limestone

Fossiliferous Limestone with Rugosa (order) and Crinoidea (class)

Banded Iron Formation (BIF)

Banded Iron Formation containing Hematite (Fe2O3) and Magnetite (Fe3O4)

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Sandstone (Picture Sandstone)

Arenite (primarily SiO2 with iron oxide impurities)

Fossiliferous Limestone with Brachiopod Mold

Calcium Carbonate (CaCO3) matrix containing Brachiopoda fossil impressions

Petrified Dinosaur Bone (Gembone)

Agatized Dinosaur Bone

Chert (Jasper/Mudstone)

Silicon Dioxide (SiO2)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (often called Flint when dark)

Microcrystalline silicon dioxide (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Chert (Field Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Ironstone Concretion / Limonite Node

Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O) with Goethite/Hematite

Fossilized Solitary Rugose Coral (Horn Coral)

Order: Rugosa (e.g., Grewingkia or Heliophyllum); composed of Calcite (CaCO3) or Silica (SiO2)

Jasper

Silicon Dioxide (SiO2) with impurities

Chert (often called Jasper in this color)

Microcrystalline quartz (SiO2)

Septarian Nodule (Septarian Dragon Stone)

Septarian concretion (composition: Calcite CaCO3, Aragonite CaCO3, and Limestone/Clay)

Red Jasper

Chalcedony (SiO2) with iron inclusions

Chert (variant of Flint)

Chert (SiO2)

River Pebble (Greywacke or Quartzite-rich Sandstone)

Lithic Sandstone (primarily SiO2 with rock fragments)

Jasper (Red/Green Brecciated)

Silicon Dioxide (SiO2) with iron oxide and chlorite inclusions

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)