Organic Specimen (Fossil)

Green Moss Agate

Silicon Dioxide with inclusions (SiO2 + Mn/Fe)

Ironstone Concretion

Siderite or Hematite Concretion (FeCO3 or Fe2O3)

Green Moss Agate / Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz with Iron and Manganese inclusions

Fossilized Blastoid (Sea Bud)

Pentremites sp. (Echinodermata, Blastoidea)

Fossilized Favosites Coral (Honeycomb Coral)

Favosites (extinct genus Table Coral)

Moss Agate

Chalcedony (SiO2) with inclusions of manganese or iron oxide

Calcareous Tufa (or Travertine)

Calcium Carbonate (CaCO3)

Pyrite in Slate

Iron Sulfide (FeS2) in Slate host matrix

Ambergris (Geological/Organic Specimen)

Ambra grisea (Produced by Physeter macrocephalus)

Glendonite (Calcite Pseudomorph after Ikaite)

Calcite (CaCO3) pseudomorph after Ikaite (CaCO3·6H2O)

Chert (specifically Iron-stained or Jasperoid Chert)

Microcrystalline Quartz (SiO2)

Jasper

Jasper (Silicon Dioxide) - SiO2

Chert (Polished River Pebble)

Chert (SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Chert (Banded Variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Gray Chalcedony)

Microcrystalline Quartz (SiO2)

Chert (potentially worked flint)

Cryptocrystalline microcrystalline quartz (SiO2)

Slate

Foliated Metamorphic Rock (primarily composed of Muscovite, Chlorite, and Quartz)

Chert (Flint Pebbles)

Microcrystalline Quartz (SiO2)

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Chert (with Epidote/Quartz veining)

Cryptocrystalline silica (SiO2) with Epidote/Quartz inclusions

Pyrite in Shale

Iron Sulfide (FeS2) in Sedimentary Matrix

Moss Agate

Chalcedony (Silicon Dioxide - SiO2) with inclusions

Chert Arrowhead (Projectile Point)

Microcrystalline Quartz (Chert/Flint)

Chert (Chalcedony/Jasper)

Microcrystalline Quartz (SiO2)

Banded Chert with Quartz Veining

Microcrystalline Quartz (SiO2)

Tumbled chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from the image

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Purple Agate (Dyed Chalcedony)

SiO2 (Silicon Dioxide) with organic dyes

Chert (specifically River Stone / Jasper variety)

Microcrystalline Quartz (SiO2)

Pyrite (Fool's Gold) in Matrix

Iron Disulfide (FeS2)

Chert (Nodule)

Chert (Silicon Dioxide, SiO2)

Moss Agate

Chalcedony (Silicon Dioxide) with inclusions - SiO2

Green Moss Agate

Silicon Dioxide with inclusions (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in sedimentary host rock

Chert (Flint)

Chert (Microcrystalline or cryptocrystalline Quartz, SiO2)

Chert (Flint) with Quartz Inclusions

Microcrystalline Quartz (SiO2)

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert (Jasper/Chalcedony)

Microcrystalline Silica (SiO2)

Moss Agate

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

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)