Organic (Geological Relative)

Vesicular Basalt

Aphanitic Mafic Igneous Rock (with vesicles)

Howlite

Howlite, Ca₂B₅SiO₉(OH)₅

Fossil Shark Tooth Fragment

Elasmobranchii dentition (fragment)

Limonite-stained Gossan/Ironstone

Goethite and Hematite (Fe2O3 • nH2O)

Ironstone Concretion (Boji Stone/Moqui Marble type)

Goethite/Hematite-encrusted Sandstone Concretion

Basalt

Extrusive Igneous Rock

Black Pearl (Tahitian Pearl)

Aragonite / Calcite (CaCO3) with Conchiolin

Limonite Bog Iron

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

Limonite Concretion

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

Anthracite Coal

Anthracite

Basalt

Basalt (composition of plagioclase, pyroxene, and olivine)

Epidote (Unakite-related)

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

Greenshist / Chlorite Schist

Chlorite schist (contains (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6)

Ironstone Concretion

Ferruginous Sandstone / Iron-rich Sedimentary Rock

Sandstone Geode (Ironstone Concretion)

Arenite with Limonite/Hematite matrix (SiO2 with Fe-oxides)

Basalt

Mafic extrusive igneous rock

Basalt with Olivine Phenocrysts

Extrusive Igneous Rock (Mafic)

Tufa Rock and Tumbled Gemstones

Calcareous Tufa (Calcium Carbonate, CaCO3)

Banded Calcite

Calcite (Calcium Carbonate, CaCO3)

Basalt with Amygdule

Aphanitic Mafic Volcanic Rock (Basalt) with Zeolite/Quartz Infill

Cockle Shell (Bivalve)

Cardiidae (Calcium Carbonate, CaCO3)

Travertine (used in construction, not a 'specimen' in situ)

Travertine

Vesicular Basalt

Extrusive mafic igneous rock (primarily Plagioclase feldspar and Pyroxene)

Basalt

Basalt

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Anthracite Coal

Anthracite

Basalt

Extrusive Igneous Rock

Tumbled blue-green chrysocolla (likely chrysocolla with quartz)

Chrysocolla, hydrated copper aluminum silicate; commonly intergrown with quartz, Cu₂H₂Si₂O₅(OH)₄

Malachite-bearing copper ore

Malachite, Cu₂CO₃(OH)₂, likely mixed with chrysocolla, copper minerals, and iron oxides

Anthracite Coal

Anthracite (Carbon rank)

Pink Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Blue-green copper mineral specimen, likely chrysocolla-bearing rock

Chrysocolla, hydrated copper phyllosilicate: approximately (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O; possibly mixed with malachite or chrysocolla matrix

Limonite Geode (Ironstone Concretion)

Goethite/Limonite FeO(OH)·nH2O

Ironstone Concretion (Moqui Marble)

Iron-oxide concretion (Fe2O3 / FeO(OH))

Basalt

Extrusive Igneous Rock

Ironstone Concretion (Limonite/Goethite)

Goethite-rich Concretion (FeO(OH))

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Basalt (Vesicular)

Extrusive Igneous Rock

Ironstone Concretion / Limonite Node

Ferruginous Sedimentary Rock (composed primarily of Limonite FeO(OH)·nH2O and Goethite)

Geode / Agate Nodule

Silicon Dioxide (SiO2)

Volcanic Tuff (Breccia)

Pyroclastic Tuffaceous Rock

Basalt

Mafic volcanic rock (primarily plagioclase, pyroxene, and olivine)