Organic (Geological Relative)

Ironstone Concretion / Limonite Specimen

Goethite and Limonite (Hydrous Iron Oxides)

Ironstone Concretion (Pot Stone)

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Anthracite Coal

Anthracite (Carbon-rich metamorphic coal)

Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3 with Carotenoid pigments)

Vesicular Basalt

Aphanitic Mafic Igneous Rock (with vesicles)

Tumbled pale limestone or calcite-rich stone

Limestone, chiefly calcite (CaCO₃); exact identification is uncertain from the photograph

Howlite (tumbled stone)

Howlite, Ca₂B₅SiO₉(OH)₅

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

Travertine

Black Pearl (Tahitian Pearl)

Aragonite / Calcite (CaCO3) with Conchiolin

Copper-bearing rock, likely chrysocolla–malachite–cuprite/goethite matrix

Hydrated copper silicate/carbonate minerals, chiefly chrysocolla (Cu₂H₂Si₂O₅(OH)₄·nH₂O) with possible malachite (Cu₂CO₃(OH)₂), iron oxides, and quartz

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich ironstone; commonly hydrated iron oxides, chiefly FeO(OH)·nH₂O

Limonite/goethite-rich ironstone

Hydrated iron oxides, chiefly goethite (α-FeO(OH)) and limonite (FeO(OH)·nH₂O)

Limonite-stained Gossan/Ironstone

Goethite and Hematite (Fe2O3 • nH2O)

Ironstone Concretion (Boji Stone/Moqui Marble type)

Goethite/Hematite-encrusted Sandstone Concretion

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Basalt

Extrusive Igneous Rock

Limonite Bog Iron

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

Epidote (Unakite-related)

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

Unidentified brown mineral/rock fragment

Indeterminate from image; possibly iron-stained quartz, feldspar, or weathered limonite

Ironstone Concretion

Ferruginous Sandstone / Iron-rich Sedimentary Rock

Limonite Concretion

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

Greenshist / Chlorite Schist

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

Tumbled blue-gray stone, likely sodalite or blue aventurine

Probably sodalite (Na₈Al₆Si₆O₂₄Cl₂); exact identification requires testing

Basalt

Basalt (composition of plagioclase, pyroxene, and olivine)

Weathered vesicular volcanic rock, likely pumice or scoria

Vesicular rhyolitic pumice or basaltic scoria; exact identification requires a clearer image and tests

Polished bumblebee jasper (likely)

Calcite–sulfur-rich volcanic breccia, commonly sold as “bumblebee jasper”

Polished malachite

Malachite (Cu₂CO₃(OH)₂), a hydrated copper carbonate hydroxide

Weathered vesicular volcanic rock

Likely basaltic andesite or scoriaceous basalt; exact identification requires fresh surface and testing

Sandstone Geode (Ironstone Concretion)

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

Turquoise ring cabochon

Turquoise, hydrated copper–aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O; likely stabilized or treated matrix turquoise

Quartz-veined Sandstone

Quartzite-veined Arenite / SiO2 and quartz sand

Malachite cabochon

Malachite, Cu₂CO₃(OH)₂

Chrysocolla-bearing copper ore

Chrysocolla (hydrated copper aluminosilicate), likely with malachite, azurite, or limonite

Iron-rich concretion (likely limonite/goethite)

Limonite–goethite aggregate; commonly hydrated iron oxides, approximately FeO(OH)·nH₂O

Howlite

Howlite, Ca₂B₅SiO₉(OH)₅

Basalt

Mafic extrusive igneous rock

Basalt with Olivine Phenocrysts

Extrusive Igneous Rock (Mafic)

Banded Calcite

Calcite (Calcium Carbonate, CaCO3)

Basalt with Amygdule

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

Vesicular Basalt

Extrusive mafic igneous rock (primarily Plagioclase feldspar and Pyroxene)

Tufa Rock and Tumbled Gemstones

Calcareous Tufa (Calcium Carbonate, CaCO3)