Not A Geological Specimen

Native Gold Nugget

Native Gold (Au)

Calcareous Tufa (Tufa)

Precipitated Calcium Carbonate (CaCO3)

Pegmatite

Granitic pegmatite, likely quartz and feldspar with dark mica (biotite)

Banded iron formation fragment (ironstone)

Banded iron formation; chiefly hematite/magnetite with chert (SiO₂)

Porphyry (Porphyritic Basalt / Porphyritic Andesite)

Porphyritic Igneous Rock

Weathered iron-rich rock, possibly limonite-bearing sandstone

Limonite/goethite mixture, approximately hydrated iron oxides (FeO(OH)·nH₂O), possibly coating sandstone or ironstone

Ironstone concretion (likely limonite/goethite-rich)

Iron-oxide/oxyhydroxide-rich concretion, chiefly goethite (FeO(OH)) and limonite; identification from the photo is provisional

Banded Iron Formation (BIF)

Banded Iron Formation (SiO2 + Fe2O3)

Chert / Flint (Arrowhead Artifact)

Microcrystalline quartz (SiO2)

Weathered green metamorphic rock, possibly serpentinite or greenstone

Likely serpentinite (serpentine-group minerals) or chlorite/epidote-rich greenschist; exact identification requires testing

Vesicular Basalt

Basalt (Mafic Extrusive Igneous Rock)

Man-made Jewelry Charm (Enameled Metal)

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

Granite (likely biotite granite or granodiorite)

Coarse-grained granitoid; mainly quartz (SiO₂), feldspar, and biotite/amphibole

Banded Iron Formation (BIF) / Chert

Banded Iron Formation (SiO2 with Fe2O3 / Fe3O4)

Blue goldstone (man-made glass)

Copper-bearing aventurine glass; synthetic silicate glass

Septarian Nodule

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

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

Granite

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

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)

Honeycomb Coral Fossil

Favosites (extinct genus of tabulate coral)

Rounded gray stone, likely basalt or andesite

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

Weathered iron-rich river pebble

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

Unidentified orange-brown rock fragment

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

Banded iron formation fragment (likely jasper-rich ironstone)

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

Conglomerate

Conglomerate 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

Iron-rich sandstone or ferruginous rock

Ferruginous sandstone, chiefly quartz (SiO₂) cemented or stained by iron oxides such as hematite (Fe₂O₃)

Chert Nodules in Limestone / Fault Breccia

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

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Pegmatite with Quartz and Muscovite Mica

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

Basalt

Extrusive mafic igneous rock

Septarian Nodule (Septaria)

Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)

Mica-rich pegmatite (likely muscovite with quartz and feldspar)

Granitic pegmatite; chiefly muscovite mica, quartz (SiO₂), and feldspar

Sandstone (Ferruginous Concretion)

Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement

Rounded granite or granitic gneiss cobble

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

Banded Iron Formation (BIF) / Ironstone

Magnetite-Hematite Quartzite / Ironstone

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