Igneous, Sedimentary, Metamorphic, Mineral, Gemstone, Fossil, Or Meteorite

Unidentified brown rock fragment

Indeterminate from image; likely a weathered iron-rich lithic fragment

Unidentified small rock fragments

Indeterminate from image; possibly quartz-rich material

Unidentified weathered rock fragments

Likely mixed silicate rocks; specific identification requires testing

Weathered quartz-rich sandstone, possibly iron-stained quartzite

Quartz sandstone (quartz arenite), SiO₂-rich; exact identification requires hardness and texture tests

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Weathered quartz-rich rock fragment

Likely quartz-bearing sandstone or granitic rock; exact identification is uncertain from the image

Blue glass-like bead or gemstone keychain ornament

Indeterminate; likely cobalt-blue glass or synthetic blue spinel, not identifiable as a natural mineral from the image

Likely assorted beach/river pebbles

Undetermined mixed lithologies; visible pieces may include quartz-rich and volcanic rocks

Pyrite

Iron Disulfide (FeS2)

Hypersthene

Enstatite-Ferrosilite series, (Mg,Fe)2Si2O6

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hematite

Iron Oxide (Fe2O3)

Fossiliferous limestone (likely crinoidal or shell limestone)

Calcite-rich limestone; predominantly CaCO₃, with visible fossil fragments

Mixed polished river stones

Likely quartz, quartzite, chert/jasper, and possibly limestone or marble

Unidentifiable embedded dark fragment

Indeterminate; possibly a dark silicate mineral or lithic inclusion

Dark metallic-looking mineral specimen, possibly magnetite

Magnetite (Fe₃O₄), tentative identification

Vesicular basalt (weathered lava rock)

Basalt, a fine-grained mafic volcanic rock composed chiefly of plagioclase feldspar, pyroxene, and commonly olivine

Hematite pseudomorph after a fossil or mineralized object (likely iron-oxide concretion)

Hematite, Fe₂O₃, possibly limonite/goethite-bearing

Likely weathered iron-rich pebble (brown sandstone or ironstone)

Indeterminate ferruginous sandstone/ironstone; commonly quartz (SiO₂) with iron oxides such as goethite and hematite

Graphite

Graphite (Native Carbon), Formula: C

Weathered vesicular limestone or calcareous tuff

Porous calcite-rich carbonate rock; composition likely predominantly CaCO₃ (calcite), with iron-oxide staining and possible silica/clay impurities

Pyrite

Iron Sulfide (FeS2)

Weathered quartz-bearing rock fragment

Indeterminate; likely quartz-rich granite or silicified host rock with iron-oxide staining

Likely weathered quartz or feldspar grain

Uncertain; possibly quartz (SiO₂) or a feldspar mineral

Unidentified dark mineral or rock specimen

Indeterminate from the severely blurred image; possible dark igneous rock or opaque mineral

Limonite Concretion

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

Pyrite

Iron Disulfide (FeS2)

Pyrite

Iron Disulfide (FeS2)

Weathered brown stone, likely basalt or iron-stained volcanic rock

Indeterminate; possibly vesicular basalt (mafic silicate rock)

Olivine (Peridot)

Magnesium Iron Silicate (Mg, Fe)2SiO4

Concretion in Shale

Siltstone/Shale with Siderite or Calcareous concretions

Fossiliferous limestone (likely ammonite/gastropod-bearing)

Bioclastic limestone; predominantly calcite (CaCO₃)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite

Sandstone Concretion

Septarian Concretion (Nodule)

Weathered sandstone pebble

Quartz-rich sandstone, likely ferruginous sandstone

Conical fossil shell or shell fragment

Likely a gastropod shell fragment; exact taxon indeterminate from the image

Sandstone (with Concretion)

Arenite / Quartzose Sandstone

Fossil gastropod in granite-like stone

Gastropoda indet.; enclosing rock likely polished granite or gneiss

Ironstone Concretion (Limonite/Goethite)

Goethite/Limonite concretion (FeO(OH)·nH2O)

Pyrite

Iron Disulfide (FeS2)