Marble

Amber

Succinite (C10H16O)

Ironstone Concretion

Siderite or Hematite Concretion

Basalt Water-Worn Pebble

Aphanitic Mafic Igneous Rock

Diamond

Diamond (pure Carbon, C)

Sandstone (likely Arkosic or Lithic Sandstone)

Clastic Sedimentary Rock (SiO2 with assorted minerals)

Diamond

Diamond (C)

Quartz / Limestone Gravel

SiO2 (Silicon Dioxide) and CaCO3 (Calcium Carbonate)

Limestone

Calcareous sedimentary rock (CaCO3)

Sandstone (Quartz Arenite)

Sandstone (SiO2 with possible mineral cements)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Chert

Chert (SiO2)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert (Cream Variety)

Microcrystalline silica (SiO2)

Chert (Jasper/Flint variety)

Silicon dioxide (SiO2)

Silicon Carbide (Carborundum)

Silicon Carbide (SiC) / Moissanite (natural)

Diamond

Diamond (Pure Carbon, C)

Brown Chert

Cryptocrystalline Silica (SiO2)

Chert (Nodule)

Chert (variety of microcrystalline quartz, SiO2)

Basalt (Water-worn Pebble)

Basalt (Mafic volcanic rock)

Serpentinite (with Pyrite/Garnet inclusions)

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)3Si2O5(OH)4

Limestone (River Stone)

Calcium Carbonate (CaCO3)

Chert (Jasper/Quartzite river stone)

Microcrystalline Silicon Dioxide (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite/Iron Oxide inclusions

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals like Antigorite, Lizardite, and Chrysotile)

Limestone

Calcium Carbonate (CaCO3)

Fossilized Shark Tooth (Otodus obliquus)

Otodus obliquus (Mineral: Fluorapatite)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Ironstone (with Limonite/Goethite)

Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O and Hematite Fe2O3)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Olivine (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Chert (Jasper)

Silicon Dioxide (SiO2)

Chert (Jasper variety)

Microcrystalline Quartz (SiO2)

Greywacke with Quartz Vein

Greywacke (immature sandstone) with SiO2 inclusions

Fossiliferous Limestone with Crinoid Stem Impression

Calcium Carbonate (CaCO3) matrix with Crinoidea fossil

Chert (Black Chert)

Microcrystalline Silica (SiO2)

Quartz (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Ferruginous Sandstone

Arenite with Iron-Oxide Cement

Fossiliferous Limestone (Coquina-like)

Biogenic Limestone

Slate

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

Chert (often called Flint for darker varieties)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Chert (specifically Gray/Black Chert)

Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)