Organic Structure (Not A Rock)

Basalt

Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Pink Opal

Hydrated silicon dioxide (SiO2·nH2O) with inclusions

Chert (Nodule)

Silicon Dioxide (SiO2)

Chert Pebble (Flint)

Microcrystalline/Cryptocrystalline Quartz (SiO2)

Chert (Quartz Variety)

Microcrystalline Silica (SiO2)

Chert (variations include Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Moss Agate

Silicon Dioxide with inclusions (SiO2 + impurities)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint Nodular)

Chert (Silicon dioxide, SiO2)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Pink Chert (Brecciated Jasmine/Jasper)

Silicon Dioxide (SiO2)

Pumice

Pumice (Amorphous volcanic glass)

Chert (varieties: Flint or Chalcedony)

Microcrystalline Quartz (SiO2)

Red Chert (Jasper)

Silicon Dioxide (SiO2)

Chert (and its variety Flint)

Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz

Petrified Wood

Silicified Wood (SiO2)

Coquina / Fossiliferous Limestone

Coquina (composed primarily of Calcium Carbonate / CaCO3)

Quartzite River Pebble

Quartzite (primarily Silicon Dioxide, SiO2)

Porphyritic Basalt

Porphyritic Basalt (with Plagioclase phenocrysts)

Smoky Quartz

Silicon Dioxide (SiO2)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Chert (Brown Variety)

Silicon dioxide (SiO2)

Quartz on Matrix

Silicon Dioxide (SiO2)

Ferruginous Sandstone (Ironstone)

Sandstone with Hematite/Goethite cement (SiO2 + FeO(OH))

Chert (Nodule)

Chert (SiO2)

Petrified Wood

Silicified wood (Quartz, SiO2)

Basalt with Quartz/Calcite Veins

Amygdaloidal Basalt (SiO2 or CaCO3 inclusions)

Quartzite River Rock

Quartzite (primarily SiO2)

Manganese Oxide Crust on Limestone

Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3

Sandstone (Fossiliferous)

Arenite / Clastic Sedimentary Rock

Moonstone

Orthoclase (Potassium Aluminum Silicate), Formula: (K,Na)AlSi3O8

Basalt with Calcite Veins

Basalt (containing CaCO3 inclusions)

Quartz Vein in Host Rock

Quartz (SiO2) in Mafic or Sedimentary Matrix

Schist

Mica Schist (contains muscovite/biotite and quartz)

Sandstone (Ferruginous/Banded)

Clastic Terrigenous Sandstone (SiO2 with Fe2O3 cement)

Banded Sandstone

Arenite (with iron oxide banding)

Sandstone (Banded Sandstone)

Clastic Sedimentary Rock (primarily SiO2 with iron oxide impurities)

Granite (tumbled pebble)

Granite (Plutonic Igneous Rock)

Sandstone (Wonderstone)

Arenite (composed primarily of SiO2 with Fe2O3 impurities)

Quartz (Milky/Crystalline)

Silicon Dioxide (SiO2)