Organic (Zoogenic)

Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Petrified Wood

Silicified Wood (SiO2)

Chert (Jasper variation)

Chert (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Septarian Nodule (Dragon Stone)

Septarian Geode (CaCO3 + Mg + Fe)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Chert (Brecciated or Veined)

Silicon Dioxide (SiO2)

Chert (Iron-Stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Moss Agate

Chalcedony (Silicon Dioxide with inclusions) - SiO2

Petrified Wood

Silicified Wood (SiO2)

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Chert (Green variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Petrified Wood (Agatized/Silicified Wood)

Silicified Wood / Chalcedony (SiO2)

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Jasper

Jasper (Silica-rich microcrystalline Quartz, SiO2 with Fe2O3 impurities)

Chert (Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Shale with Vein Infillings

Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)

Jasper (Petrified Wood variant)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Stromatolite (Jasper-replaced)

Fossilized Stromatolite (Cyanobacteria / Cryptozon / Silica SiO2)

Grey and White Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Petrified Wood

Silicified Wood (SiO2)

Chert (Quartz Variety)

Microcrystalline Silica (SiO2)

Chert (specifically Tan/Yellow Chert)

Chert (Microcrystalline or Cryptocrystalline Silica, SiO2)

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Jasper with Quartz Vein

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Yellow Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with iron oxide (Limonite/Goethite) inclusions

Fossil Coral (Favosites Honeycomb)

Favosites (Genus), Phylum Cnidaria, Class Anthozoa

Petrified Wood

Silicified Wood (SiO2)

Jasper (Iron-stained Chert)

Silicon Dioxide (SiO2) with impurities of Hematite or Goethite

Septarian Nodule

Septarian Concretion

Chert (White/Light Tan)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood (Agatized/Silicified Wood)

Silicified Wood (SiO2)

Chert (Nodular)

Chert (SiO2 - Microcrystalline Quartz)