Marble

Chert Pebble/Nodule

Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)

Black Chert

Chert (microcrystalline quartz)

Diamond (Rough)

Diamond (C)

Ironstone Concretion (Limonite/Goethite)

Ironstone (primarily FeO(OH)·nH2O)

Diamond (Cluster Ring)

Carbon (C)

Pearl

Calcium carbonate (CaCO3) in the form of aragonite or calcite

Sandstone (likely Arkose)

Arenite (Feldspathic Sandstone / Arkose)

Blue Calcite

Calcium Carbonate (CaCO3)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Diamond (or Cubic Zirconia imitation)

Carbon (C) - Native Element

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Oolitic Chert

Ooidal Microcrystalline Quartz (SiO2)

Siltstone

Siltstone (primarily composed of SiO2 with various clay minerals)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Red Jasper

Silicon Dioxide (SiO2) with iron inclusions

Chert (with Quartz Vein)

Chert (Siliceous sedimentary rock, predominantly Microcrystalline Quartz SiO2)

Coquina

Coquina Limestone

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Chert (Flint)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2)

Chert (and Limestone) River Cobble

Microcrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)

Diamond

Carbon (C)

Chert / Jasper

Microcrystalline Quartz (SiO2)

Fossiliferous Limestone with Rugose Coral

Calcite (CaCO3) matrix containing Rugosa (order of extinct solitary and colonial corals)

Rough Amber (likely Copal or immature Amber)

Organic gemstone / Succinite (if Baltic)

Sandstone

Arenite (primarily SiO2 with trace Fe2O3)

Rugose Coral (Horn Coral)

Order Rugosa (extinct fossilized coral)

Quartz Pebble

Silicon Dioxide (SiO2)

Peridot (Olivine)

Olivine (Magnesium Iron Silicate - (Mg, Fe)2SiO4)

Coquina Jasper

Fossiliferous Chalcedony (SiO2)

Fossiliferous Limestone with Rugose Coral

Rugosa (order), typically preserved in CaCO3 (Calcite)

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone (Weathered Coastal Boulder)

Arenite (composed primarily of SiO2)

Chert (Arrowhead Artifact)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Limonite (Iron-rich Siltstone / Sandstone base)

Hydrous ferric oxide mixture (FeO(OH)·nH2O)

Grey Basalt Pebble

Basalt (Aphanitic Mafic Volcanic Rock)

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (SiO2 based)

Ferruginous Sandstone

Arenite with Iron-oxide cement (composed of Quartz and Limonite/Hematite)

Sandstone (specifically Lithic or Quartz Arenite)

Arenite (composed primarily of SiO2)

Sandstone (Graywacke type)

Clastic Sedimentary Rock (Lithic Sandstone)

Fossilized Shark Tooth

Scapanorhynchus (Sand Tiger Shark relative)