Organic Structure (Not A Rock)

Chert / River Jasper

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Glauconitic Sandstone (Greensand)

Glauconitic Quartz Arenite (containing Glauconite, (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)

Chert (Common Opal/Jasper variety)

Microcrystalline Quartz (SiO2) with hydration

Manganese-coated Sandstone

Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)

Shale (sub-type: Carbonaceous Shale)

Lutaceous Sedimentary Rock

Chert (Quartz Variety)

Chert (mostly SiO2 / Silicon Dioxide)

Amber

Resinite / Fossilized Tree Resin

Portable Ceramic Space Heater

Polished Acrylonitrile Butadiene Styrene (ABS) Plastic with Ceramic Heating Elements

Chert Nodule

Microcrystalline Silica (SiO2)

Chert (often called Jasper or River Rock)

Chert (SiO2)

Fossilized Horn Coral

Order Rugosa (Rugose Coral)

Moss Agate

Silicon Dioxide with inclusions (SiO2 + Fe/Mn/Mg)

Chert (variously identified as Flint)

Microcrystalline Quartz (SiO2)

Chert (Chert / Flint)

Silicon dioxide (SiO2) - Microcrystalline quartz

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Sandstone Chert Concretion

Silica-cemented Concretion (primarily SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2)

Chert (Brecciated or Veined)

Silicon Dioxide (SiO2)

Chert with Quartz Veining

Silicon Dioxide (SiO2)

Fossilized Coral

Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)

Shale with Plant Fossils / Carbonaceous Shale

Laminated Mudrock (Siliciclastic)

Petrified Wood

Silicified Wood (primarily Chalcedony or Quartz, SiO2)

Chert (and/or River Pebble)

Microcrystalline silica (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Moss Agate

Chalcedony (SiO2) with inclusions of hornblende or chlorite

Chert (Nodular)

Microcrystalline Silica (SiO2)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Crinoid Fossil in Limestone

Crinoid (Class Crinoidea) in Fossiliferous Limestone (CaCO3)

Chert (Nodular Chert)

Silicon Dioxide (SiO2)

Banded Chert (River Siltstone)

Microcrystalline Quartz (SiO2)

Moss Agate

Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)

Chert (Arrowhead/Artifact Fragment)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Red Jasper

Jasper (Silicon Dioxide, SiO2)

Chert (with Liesegang Banding)

Microcrystalline quartz (SiO2)

Chert / Pink Flint

Cryptocrystalline Quartz (SiO2)

Moss Agate / Chalcedony

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Chert (Field Stone)

Microcrystalline / Cryptocrystalline Quartz (SiO2)

Chert (Quartz Pebble)

Silicon Dioxide (SiO2)