Not A Geological Specimen

Biotite schist (probable mica schist)

Mica schist; chiefly quartz, biotite mica, and feldspar

Mica Schist (with Muscovite)

Muscovite Mica Schist (KAl2(AlSi3O10)(F,OH)2)

Weathered iron-rich rock fragment

Likely limonite/goethite-rich ironstone; exact identification requires testing

Banded iron formation fragment

BIF; hematite–magnetite–chert/quartz assemblage

Foliated metamorphic rock, likely mica schist

Muscovite- or biotite-bearing schist, commonly quartz–feldspar schist

Sandstone Moqui Marble (Concretion)

Iron oxide concretion (Hematite/Goethite and Quartz)

Ferruginous Sandstone

Arenite with Iron-Oxide cement (primarily Fe2O3 • nH2O)

Goldstone beads (likely brown goldstone)

Man-made copper-bearing glass; not a natural mineral. Often sold as “aventurine glass.”

Mixed mineral and rock collection

Predominantly quartz varieties, including amethyst, plus likely calcite, feldspar, mica, and miscellaneous polished stones

Blue tumbled glass or dyed stone (uncertain)

Unidentified; appearance is consistent with blue glass, but a blue mineral such as dyed quartz cannot be ruled out from the photo

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Native metal specimen, likely galena or metallic slag

Probably galena (lead sulfide, PbS); identification is uncertain from the image alone

Sandstone Pebble (River Rock)

Sandstone (Quartz-rich sedimentary rock with iron oxide staining)

Green glass-like cabochon, likely synthetic glass or resin

Unidentified green transparent material; possibly molded glass, synthetic spinel, or resin

Biotite-rich granite or granodiorite fragment

Coarse-grained felsic intrusive rock; mainly quartz (SiO₂), feldspar, and biotite mica

Unidentified dark reddish-brown rock or mineral specimen

Indeterminate from the blurred image; possibly iron-stained quartz, jasper, or a metallic sulfide-bearing rock

Polished black stone carving, likely soapstone/steatite

Steatite (massive talc), Mg₃Si₄O₁₀(OH)₂; exact material cannot be confirmed from the image

Weathered iron-rich rock, possibly limonite-bearing sandstone or laterite

Goethite–hematite (FeO(OH)–Fe₂O₃) in a silicate-rich matrix; exact identification requires testing

Flint (or Chert)

Microcrystalline quartz (SiO2)

Weathered iron-rich rock, possibly limonite-bearing sandstone or laterite

Limonite/goethite-rich ferruginous rock; exact identification requires testing

Druzy Quartz on Chert/Siltstone

Silicon Dioxide (SiO2) on Microcrystalline Silica/Siltstone matrix

Iron-rich sandstone or weathered ironstone

Ferruginous sandstone; primarily quartz (SiO₂) cemented or stained by iron oxides, chiefly hematite (Fe₂O₃) and goethite (FeO(OH))

Green aventurine (rough quartz)

Quartz, SiO₂, with green fuchsite mica inclusions

Gossan (Iron Hat) with Quartz and Chlorite

Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite

Worked flint/chert artifact

Microcrystalline quartz (chalcedony), SiO₂; likely a knapped flint or chert flake/core fragment

Small metallic mineral fragment

Unidentified metallic sulfide or native-metal fragment

Granite or granitic gneiss

Quartz–feldspar–mica rock; likely granitoid, possibly weakly gneissic

Banded iron formation fragment

Banded iron formation (BIF), composed mainly of hematite/magnetite and chert (SiO₂)

Pyrite-bearing dark igneous rock, possibly basalt

Likely basalt or mafic volcanic rock with disseminated pyrite (FeS₂); identification is provisional from the photograph

Emerald and diamond ring

Emerald: beryl, Be3Al2Si6O18, colored green by chromium and/or vanadium; surrounding stones appear to be diamonds, crystalline carbon (C)

Basalt in a vesicular volcanic host rock

Basalt, likely with secondary zeolite or calcite infill

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)

Likely iron-rich sandstone or weathered hematite-bearing rock

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂ with iron oxides such as hematite/goethite)

Kaibab Limestone

Calcitic limestone, predominantly calcium carbonate (CaCO₃)

Concrete-like limestone or cemented carbonate rock

Likely limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image

Weathered gray sandstone or fine-grained metamorphic rock

Likely quartz-rich sandstone (quartz arenite), possibly weakly metamorphosed metasandstone

Banded iron formation fragment

Banded iron formation (BIF), chiefly hematite/magnetite and chert (SiO₂)

Iron-rich sandstone or lateritic ironstone

Ferruginous sandstone/ironstone, chiefly quartz (SiO₂) with iron oxides and hydroxides such as hematite (Fe₂O₃) and goethite (FeO(OH))

Tumbled dark mineral on a polished brown stone slab

Likely quartz-rich chalcedony or jasper slab with a dark metallic mineral inclusion; exact identification is uncertain from the photograph

Unidentified small mineral fragment

Possibly quartz or feldspar-bearing rock; exact identification is uncertain from the image

Weathered fossiliferous limestone

Calcitic limestone, predominantly calcium carbonate (CaCO₃), possibly bioclastic limestone

Faceted gemstone pendant, likely quartz or citrine

Indeterminate from photograph; likely quartz (SiO₂), possibly yellow citrine or treated quartz