Not A Geological Specimen

Sandstone Concretion

Clastic Sedimentary Rock (primarily SiO2 with mineral cement)

Vesicular basalt pebble

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

Raw dark metamorphic rock, likely schist or slate

Mica schist or phyllite; commonly quartz–mica–chlorite aggregate

Polished garnet-bearing gneiss

Biotite-quartz-feldspar gneiss with almandine garnet (garnet: Fe₃Al₂(SiO₄)₃)

Quartz with Chlorite / Greenschist

Quartz vein in Greenschist (SiO2 with Chlorite group minerals)

Hematite / Red Ochre (Iron Ore)

Hematite (Fe2O3)

Biotite Schist

Biotite-rich Schist

Quartz-rich pegmatite fragment

Granite/pegmatite; chiefly quartz (SiO₂) and feldspar, with possible biotite or tourmaline

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

Limonite/goethite-rich material; composition commonly FeO(OH)·nH₂O with clay and quartz impurities

Ferruginous Sandstone (Ironstone)

Sandstone with Hematite/Goethite cement (SiO2 + FeO(OH))

Iron-stained sandstone or weathered ironstone

Quartz-rich sandstone with iron-oxide cement, chiefly hematite (Fe₂O₃) and/or goethite (FeO(OH))

Basalt with Peridotite (Olivine) Xenolith

Olivine-rich Peridotite (Dunite) xenolith in Vesicular Basalt; chemical formula (Mg,Fe)2SiO4

Quartz-veined metamorphic rock, likely quartzite or quartz-rich schist

Quartz (SiO₂) vein in a foliated, quartz-rich metamorphic host; exact rock type cannot be confirmed from the image alone

Banded metamorphic rock, likely mica schist or gneiss

Mica schist/gneiss, chiefly quartz, feldspar, biotite and muscovite

Unidentified gray stone/concrete-like fragment

Indeterminate; likely a fine-grained carbonate or cementitious geological fragment

Biotite (Mica)

Biotite group (K(Mg,Fe)3AlSi3O10(F,OH)2)

Green Glass Cullet / Recycled Glass

Amorphous Silicon Dioxide (SiO2) with various metal oxides

Inukshuk Rock Sculpture (composed of Granite, Slate, and Amethyst)

Silicon Dioxide (Amethyst portion, SiO2) with mixed silicate rock assemblage

Asphalt (Road Aggregate)

Asphalt concrete / Bituminous mixture

Weathered granite cobble

Granite (quartz–feldspar–mica rock; commonly containing quartz, K-feldspar, plagioclase, and biotite)

Basalt cobble in glacial till or gravel

Basalt, a fine-grained mafic volcanic rock; likely an altered basalt clast

Jewelry Chain with Blue and Clear Gemstones (Likely Cubic Zirconia)

Cubic Zirconia (ZrO₂), Silver or White Gold/Platinum Alloy

Vesicular volcanic rock (likely pumice or scoria)

Pumice/scoria; predominantly volcanic glass and feldspar-rich silicate material

Cullet Glass (Slag Glass)

Amorphous Silicon Dioxide (Industrial Byproduct)

Iron-rich banded iron formation fragment (likely hematite/magnetite ore)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica (SiO₂)

Acrylic or Resin (Synthetic Imitation)

Polymethyl Methacrylate (PMMA) or Polyepoxide

Moqui Marble (Ironstone Concretion)

Goethite-Hematite Sandstone Concretion

Weathered iron-rich sandstone or siltstone

Clastic siliciclastic sedimentary rock, likely ferruginous sandstone/siltstone (quartz-rich, Fe-oxide cement)

Rounded iron-rich cobble (likely lateritic sandstone or ironstone)

Ferruginous sandstone/ironstone; chiefly quartz (SiO₂) with iron oxides, especially hematite (Fe₂O₃) and goethite (FeO(OH))

Jasper (specifically Chert/Ironstone)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Iron-rich sandstone or weathered laterite

Ferruginous sandstone; chiefly quartz (SiO₂) cemented by iron oxides/hydroxides

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

Laterite/limonite mixture; primarily hydrated iron oxides such as goethite (FeO(OH)) and iron-rich clay minerals

Fordite

Anthropogenic paint-rock

Uncertain fine-grained rock or mineral-bearing specimen

Indeterminate; possible quartz- or feldspar-bearing matrix with reflective grains

Quartz pebble in concrete

Quartz (SiO₂), embedded in Portland-cement concrete

Bronze or iron-age decorated pottery sherd

Archaeological ceramic fragment; likely fired clay with impressed or molded decoration, not a natural rock

Porous fossiliferous limestone

Calcitic limestone, predominantly calcium carbonate (CaCO₃), possibly bioclastic or weathered reef limestone

Unidentified dark gray rock fragment

Likely fine-grained basalt or andesite; exact identification requires testing

Vesicular basalt

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

Mica Schist

Schist (muscovite-biotite rich)

Weathered iron-rich rock fragment

Indeterminate; likely limonite/goethite-bearing sandstone or laterite

Chert Nodule

Microcrystalline Quartz (SiO2)