Not A Geological Specimen

Granite

Coarse-grained felsic intrusive igneous rock, mainly quartz, alkali feldspar, plagioclase, and mica

Vesicular Basalt

Basalt (Mafic Extrusive Igneous Rock)

Weathered iron-rich river pebble

Ferruginous sandstone or ironstone; composition likely quartz with iron oxides (hematite/goethite)

Honeycomb Coral Fossil

Favosites (extinct genus of tabulate coral)

Banded Iron Formation (BIF) / Chert

Banded Iron Formation (SiO2 with Fe2O3 / Fe3O4)

Chert Nodules in Limestone / Fault Breccia

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3) matrix

Conglomerate

Conglomerate rock

Septarian Nodule

Septarian Concretion (CaCO3, CaMg(CO3)2, SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Rounded dark river cobble, likely basalt

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

Weathered quartz-rich pebble (probable quartzite or quartz vein fragment)

Quartzite, predominantly silicon dioxide (SiO₂); exact identification is uncertain from the photograph

Banded Iron Formation (Jasper / Hematite Ore)

Banded Iron Formation (BIF) / Hematite-Quartz Rock

Chalcedony in Limestone Host Rock

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Unidentified orange-brown rock fragment

Likely weathered iron-rich volcanic rock or ochre-bearing material; exact identification is impossible from the blurred image

Rounded gray stone, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; likely basalt (plagioclase ± pyroxene, possibly olivine)

Septarian Nodule (Septaria)

Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)

Banded iron formation fragment (likely jasper-rich ironstone)

Banded iron formation (BIF), commonly hematite/goethite with chert or jasper; Fe₂O₃/FeO(OH) and SiO₂

Rounded granite or granitic gneiss cobble

Granite; predominantly quartz, feldspar, and minor biotite/amphibole

Red Sandstone Pebble

SiO2 with Fe2O3 (Quartz sandstone with hematite coating)

Chert Arrowhead (Flint Projectile Point)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Flint with Iron Oxide Inclusions

SiO2 (Microcrystalline Quartz) with Goethite/Limonite inclusions

Basalt

Extrusive mafic igneous rock

Banded Iron Formation (BIF)

Banded Iron Formation (Magnetite/Hematite-Chert)

Likely slate or fine-grained metamorphic rock

Slate/phyllite; predominantly fine-grained mica, chlorite, and quartz

Pegmatite with Quartz and Muscovite Mica

Granitic Pegmatite (KAl2(AlSi3O10)(OH)2 + SiO2)

Fossiliferous Limestone

Biomicrite / Limestone with fossils

Banded Iron Formation (BIF) / Ironstone

Magnetite-Hematite Quartzite / Ironstone

Sandstone (Ferruginous Concretion)

Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement

Metal Alloy (Jewelry)

Not a naturally occurring rock or mineral; likely a metal alloy for jewelry. Possible compositions include sterling silver (92.5% silver, 7.5% copper), or other silver/gold alloys.

Man-made Jewelry Charm (Enameled Metal)

Not a natural mineral; composed of base metal alloy (likely zinc or brass) and epoxy resin/enamel.

Limonite (Ironstone)

Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)

Likely slate or fine-grained metamorphic rock

Slate; predominantly microscopic mica, quartz, and clay-derived minerals

Blue sea glass or blue glassy mineral fragment

Uncertain; likely man-made soda-lime glass, not a natural mineral

Carved Mottled Greenish-Yellow Crystal/Glass Object

Unknown; possibly a form of quartz (chalcedony/jadeite/nephrite) or glass/resin.

Unidentifiable embedded dark fragment

Indeterminate; possibly a dark silicate mineral or lithic inclusion

Weathered limestone

Limestone; predominantly calcite (CaCO₃)

Banded Gneiss

Gneiss

Moqui Marble (Iron-Oxide Concretion)

Iron Oxide Concretion (Fe2O3)

Likely coral fragment or porous limestone

Calcareous biogenic carbonate, primarily calcite (CaCO₃); exact identification is uncertain from the image

Biotite-rich granite or granitic gneiss

Granite; quartz–feldspar–biotite assemblage

Iron-rich laterite (hematitic limonite)

Laterite composed mainly of hematite (Fe₂O₃), goethite (FeO(OH)), and hydrated iron oxides

Banded Iron Formation (BIF)

Banded Iron Formation (predominantly Hematite Fe2O3 and Magnetite Fe3O4 with Chert SiO2)