Not A Geological Specimen

Likely brecciated jasper or iron-stained quartz-rich rock

Jasper-bearing breccia; exact identification requires testing

Quartzite

Quartzite (SiO2)

Ironstone concretion

Iron-oxide-rich sedimentary concretion, likely dominated by goethite and/or hematite

Chert / Flint Nodule

Microcrystalline Quartz (SiO2)

Rounded gray pebble

Unidentified lithic pebble; likely quartz-rich sandstone, quartzite, or fine-grained igneous rock

Chert (Pink Jasper)

Microcrystalline Quartz (SiO2)

Dark gray slate or phyllite cobble

Slate–phyllite, composed mainly of fine-grained mica, quartz, and chlorite

Quartz vein in dark host rock

Milky quartz (SiO₂) in an unidentified dark metamorphic host, possibly amphibolite or schist

Conglomerate

Conglomerate Rock

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (SiO2)

Unakite

Unakite (epidote-bearing altered granite; mainly pink potassium feldspar, green epidote, and quartz)

Quartz Pebble in Sandstone matrix

Quartz Conglomerate (SiO2 matrix)

Quartz-veined Metamorphic Rock

Quartz-veined Schist or Gneiss

Milky Quartz (Gold-bearing Prospecting Specimen)

Silicon Dioxide (SiO2)

Quartz Breccia with Iron Staining

Tectonic or Sedimentary Breccia (SiO2 with Fe2O3)

Banded Iron Formation (BIF) / Banded Sandstone Nodule

Hematite-rich Sandstone / Ferruginous Chert

Weathered iron-rich concretion or sedimentary rock

Likely ferruginous sandstone or ironstone concretion; exact identification is not possible from the image alone

Likely garnet-bearing metamorphic rock

Possibly garnetiferous mica schist; exact identification requires close examination or testing

Petrified Wood

Silicified Wood (SiO2)

Dinosaur Bone Fossil

Permineralized Dinosaur Bone

Mica-rich schist (likely biotite schist)

Mica schist, composed mainly of biotite and/or muscovite with quartz and feldspar

Likely amphibolite

Amphibolite, composed chiefly of hornblende and plagioclase feldspar

Quartzite with Mafic Intrusion (Gneiss/Schist Contact)

Metamorphic Quartzite (SiO2) with Amphibole/Biotite Schist

Dark polished stone, possibly a pebble

Undetermined; image lacks detail for reliable identification

Tumbled granite (likely granitic gneiss)

Granite; primarily quartz (SiO₂), feldspar, and mica, possibly with metamorphic foliation

Likely garnet-bearing schist

Mica schist, possibly garnet-bearing; exact identification requires closer examination

Banded gneiss pebble

Gneiss, composed chiefly of quartz, feldspar, and mica/amphibole

Granite Pegmatite with Muscovite Mica

Granite Pegmatite (Silicon Dioxide and complex silicates)

Mica-rich metamorphic rock (likely schist)

Mica schist, likely muscovite- or biotite-bearing; exact identification is uncertain from the photograph

Glacial erratic boulder

Likely weathered sandstone or quartzitic sandstone; exact identification requires a fresh surface and locality

Fulgarite

Fulgurite (Lechatelierite / Vitrified Sand)

Fossil Coral

Hexagonaria or Rugose coral fossil in limestone/silica matrix

Greenschist

Greenschist (Chlorite Schist)

Rough garnet-bearing rock, likely garnet-mica schist

Garnet (commonly almandine, Fe₃Al₂(SiO₄)₃) in a mica- and quartz-rich metamorphic matrix; exact identification is uncertain from the photo

Vesicular volcanic rock (likely pumice)

Pumice, a highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition

Weathered sandstone pebble

Quartz-rich sandstone, likely arkosic or lithic sandstone

Blue crystal pendant (likely blue glass or synthetic crystal)

Not identifiable from the image; possibly synthetic quartz or glass, rather than a natural mineral

Banded Calcite (often commercially called 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Kaolinite-rich claystone (kaolin)

Kaolinite, Al₂Si₂O₅(OH)₄, likely in a clay-rich rock

Amygdaloidal Basalt with Quartz Infill

Amygdaloidal Basalt (SiO2 infill)

Chalcedony in Host Rock

Chalcedony (SiO2)