Not A Geological Specimen

Eclogite with Diamond (Kankanite/Nodule)

Ultramafic Xenolith / Diamond-bearing Eclogite

Conglomerate (likely pebble-rich rock)

Lithified conglomerate; exact composition cannot be determined from the photo

Likely amphibolite (dark hornblende-rich rock)

Amphibolite, typically composed mainly of hornblende and plagioclase feldspar

Likely basalt (dark volcanic rock)

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

Rough Chalcedony / Jasper Nodules

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Porphyritic volcanic rock (likely andesite)

Porphyritic andesite; exact identification requires closer examination

Weathered iron-rich concretion or limonite/goethite nodule

Limonite (largely hydrated iron oxides; commonly goethite, FeO(OH), and hematite, Fe₂O₃)

Petrified Wood

Silicified Wood (SiO2)

Iron-stained quartz-rich rock (likely ferruginous quartzite)

Quartz (SiO₂) with iron oxides, chiefly hematite/goethite; exact rock type cannot be confirmed from the photo

Auriferous Quartz (Gold-bearing Quartz)

Silicon Dioxide (SiO2) with trace Gold (Au) and Iron Oxides

Banded Iron Formation (Fragment)

Banded Iron Formation (BIF)

Siderite Concretion in Shale

Iron carbonate (FeCO3) in Mudstone/Shale matrix

Granite fragment (likely weathered granite)

Granite; mainly quartz (SiO₂), feldspar, and mica (biotite/muscovite)

Pink granite

Felsic intrusive igneous rock; predominantly potassium feldspar, quartz, and biotite/hornblende

Oolitic Ironstone

Sedimentary Ooidal Ironstone (Limonite/Hematite mixture)

Flint with Fossil

Silicon dioxide (SiO2) microcrystalline quartz with fossiliferous inclusions

Chert (specifically a Lithic Flake)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Banded gneiss

Gneiss, typically quartz–feldspar–mica assemblage

Manganese Dendrite on Siltstone

Manganese Oxide (pyrolusite or psilomelane) Dendrites

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (SiO2 permineralization)

Septarian Nodule (Dragon Stone)

Septarian Nodule (Calcium Carbonate/Aragonite/Calcite Concretion)

Petrified Wood

Silicified Wood (SiO2)

Mica-rich schist (probable)

Mica schist, likely muscovite–chlorite schist; exact minerals cannot be confirmed from the image

Petrified Wood

Silicified Wood (primarily SiO2)

Tektite (Indochinite)

Impact Glass (SiO2 + Al2O3)

Moqui Marble (Shaman Stone)

Iron Oxide Concretion (Hematite/Goethite)

Terrazzo flooring containing marble aggregate

Marble (recrystallized calcite, CaCO₃) aggregate in cementitious terrazzo

Petrified Wood

Silicified Wood (SiO2)

Devil's Toenail

Gryphaea (extinct genus of foam oysters, typically composed of Calcite CaCO3)

Favosites Fossil (Honeycomb Coral)

Favosites alpenensis (Order: Tabulata)

Black-veined pebble, likely basalt in a weathered host rock

Probable basaltic dike or vein in altered volcanic rock; exact identification requires testing

Limonite or Ironstone Nodule

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

Fulgurite

Fulgurite (Lechatelierite-rich fused silica)

Black basalt pebble

Basalt; fine-grained mafic volcanic rock, commonly composed of plagioclase, pyroxene, and minor olivine or magnetite

Fossil Coral (Tabulate Coral Fragment)

Anthopleura / Tabulata (CaCO3 - Calcium Carbonate)

One Pound Coin (UK)

Nickel-Brass Alloy (Cu-Zn-Ni)

Basalt

Basalt (dominated by Plagioclase Feldspar and Pyroxene)

Polished dark stone, likely basalt or slag-like volcanic rock

Probable fine-grained basalt (plagioclase–pyroxene; possibly glassy volcanic material)

Limonite (Yellow Ochre)

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

Limonite and Goethite encrusted Chert/Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O) with cryptocrystalline Silica (SiO2)