Organic (Paper And Cellulose)

Optical Calcite (Iceland Spar)

Calcite (Calcium Carbonate, CaCO3)

Granite (with Quartz Vein and Biotite)

Granite (Plutonic Igneous Rock)

Desert Rose (Baryte or Selenite)

Barium Sulfate (BaSO4) or Hydrous Calcium Sulfate (CaSO4·2H2O)

Pyrite

Iron Disulfide (FeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Agate

Silicon Dioxide (SiO2)

Horn Coral Fossil

Order Rugosa

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase + pyroxene, sometimes olivine)

Sandstone with Iron Banding

Arenite with Hematite or Limonite staining (SiO2 with Fe2O3)

Marble

Recrystallized Calcite (CaCO3)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Polished pale stone, likely limestone or quartzite pebble

Most consistent with micritic limestone (calcite, CaCO₃), though the image cannot confirm mineralogy

Orthoceras Fossil Limestone

Orthoceras (extinct genus of cephalopod); Limestone matrix (CaCO3)

Chalcedony Nodule (Carnelian/Agate)

Chalcedony (Silicon Dioxide, SiO2)

Banded Gneiss River Pebble

Gneiss

Limestone

Calcareous sedimentary rock (CaCO3)

Tumbled black stone, likely basalt or black jasper

Probably basalt (fine-grained plagioclase–pyroxene rock); exact identification is uncertain from the image

Limestone

Calcium Carbonate (CaCO3)

Red Jasper

Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)

Thunderegg (Agetized Geode nodule)

Rhyolitic Agate Nodule (SiO2 filling volcanic cavities)

Pyrite

Iron Sulfide (FeS2)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Limestone or Chalk

Calcium Carbonate (CaCO3)

Kaolinite Claystone

Al2Si2O5(OH)4 (Kaolinite)

Agate Geode / Thunderegg

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Tumbled brown-and-white feldspar-rich stone, likely granite or quartzite

Indeterminate; probably quartz–feldspar aggregate (granite) or quartzite, with iron-oxide staining

Likely anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

Quartz Pebble with Muscovite Mica

Quartzite / Quartz-Mica Schist pebble (SiO2 with KAl2(AlSi3O10)(OH)2)

Quartz with Schist/Mica Inclusions

Crystalline Silicon Dioxide (SiO2) with Phyllosilicates

Grey Slate

Foliated Metamorphic Rock (formed by low-grade regional metamorphism of shale or mudstone)

Pink Granite

Phaneritic Plutonic Rock (Felsic)

Pink Granite

Phaneritic intrusive igneous rock (high Orthoclase Feldspar content)

Diorite

Diorite (intermediate intrusive igneous rock)

Banded Sandstone

Arenite (with iron oxide banding)

Porphyritic Basalt

Basalt with plagioclase phenocrysts

Carrara Marble

Metamorphosed Limestone (principally Calcium Carbonate, CaCO3)

Marble

Recrystallized Calcite (CaCO3)

Banded Iron Formation (BIF) / Red Jasper with Hematite

Ferruginous Chert (primarily Quartz [SiO2] and Hematite [Fe2O3])

Pyrite

Iron Disulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)