Rock (Likely Sedimentary)

Sandstone

Arenite (Sedimentary Rock)

Shale (possibly Carbonaceous or Oil Shale)

Argillaceous Sedimentary Rock

Shale

Argillaceous sedimentary rock

Shale

Lutaceous Sedimentary Rock

Fossil Coral

Tabulate Coral (potentially Favosites or Calapoecia)

Gastropod Steinkern (Internal Mold Fossil)

Gastropoda (Class); Internal mold or 'Steinkern' composed of Calcium Carbonate (CaCO3) or Sedimentary matrix

Vesicular basalt (likely weathered lava rock)

Vesicular basalt; primarily plagioclase feldspar, pyroxene, and volcanic glass, with possible iron-oxide alteration

Pink chalcedony (likely rough agate/chalcedony)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-bearing

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartz chunk

Silicon dioxide (SiO2)

Iron Ore / Ironstone Concretion

Mixture of iron oxide/hydroxide minerals, likely some combination of Hematite (Fe2O3), Goethite (α-FeOOH), and Limonite (a general term for hydrated iron oxides of variable composition) or potentially Bauxite (a mixture of aluminum hydroxides, often with iron oxides, (Al(OH)3) and FeO(OH)). The visual characteristics strongly suggest iron-rich material.

Green calcite (likely)

Calcite — calcium carbonate, CaCO₃

Weathered graywacke or sandstone cobble

Lithic/feldspathic sandstone; exact identification requires a fresh break or thin section

Calcite-rich limestone (possibly fossiliferous limestone)

Calcite, CaCO₃, in a limestone matrix

Chert (Flint)

Silicon Dioxide (SiO2)

Quartz Pebble (Iron-stained)

Silicon Dioxide (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with high iron inclusion

Chert (containing Iron Oxide spots)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pink-and-gray quartz-rich pegmatite, possibly rose quartz with feldspar

Quartz (SiO₂) with K-feldspar/plagioclase; likely pegmatitic granite

Tumbled dark gray stone, likely basalt

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Chert (likely Flint)

Cryptocrystalline Quartz (SiO2)

Granite Pebble

Granite (Phaneritic intrusive igneous rock comprising Quartz, Feldspar, and Mica)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Water-worn brown chert or jasper pebble

Microcrystalline quartz (SiO₂), likely ferruginous chert/jasper

Likely weathered gray flint/chert pebble

Microcrystalline quartz (SiO₂), commonly with chalcedony and minor impurities

Chert (Beach Pebble)

Silicon Dioxide (SiO2)

Yellow Chert (Jasper)

Cryptocrystalline Quartz (SiO2)

Limestone (River or Sea Cobble)

Calcium Carbonate (CaCO3)

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Fossiliferous Limestone with Crinoid Stem

Bioclastic Limestone (CaCO3)

Fossiliferous Chert (Chert with Crinoid Stem Impression)

Chert (SiO2) with fossil Anthozoan or Crinoid columnals

Petrified Wood

Silicified wood (Quartz, Chalcedony, or Opal)

Porphyritic Rhyolite or Andesite (Porphyry)

Porphyritic igneous rock (Composition depends on exact mineralogy, often Rhyolite or Andesite)

K2 Jasper (Beads)

Granodiorite with Azurite and Malachite

River Rock (likely Quartzite or Quartz-rich Siltstone)

Quartzite (SiO2)

Chalcedony (specifically Agate or Flint)

Silicon Dioxide (SiO₂)

Granite (likely Kashmir/ivory-type granite)

Granite; chiefly quartz (SiO₂), feldspar, and mica/amphibole

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz with Limonite/Goethite staining)

Weathered iron-rich volcanic rock

Likely altered basalt or andesite with iron-oxide staining

Tumbled dark stone, possibly chert or basalt

Indeterminate; likely fine-grained basalt (plagioclase–pyroxene) or microcrystalline chert (quartz, SiO₂)