Organic (Paper And Cellulose)

Barite

Barium Sulfate (BaSO4)

Rounded greenish pebble

Indeterminate; likely weathered quartzite, greenstone, or altered volcanic rock

Petoskey Stone (Fossilized Rugose Coral)

Hexagonaria percarinata (Calcium Carbonate, CaCO3)

Kaolinite (Chalky Clay)

Kaolinite (Al2Si2O5(OH)4)

Petrified Wood

Silicified Wood (SiO2)

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Polished banded agate (likely carnelian and black agate)

Chalcedony, microcrystalline quartz (SiO₂), with iron-oxide coloration

Polished banded agate heart

Microcrystalline quartz (SiO₂), primarily chalcedony with iron-oxide inclusions

Tumbled agate (likely banded/chalcedony agate)

Microcrystalline quartz, SiO₂; chalcedony with possible iron-oxide coloration

Tumbled pale agate or chalcedony

Microcrystalline quartz (SiO₂), likely banded chalcedony/agate

Tumbled fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃), with fossil shell fragments

Black polished stone, likely basalt

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

Polished brown chalcedony (likely carnelian or sard)

Chalcedony, microcrystalline quartz (SiO₂); brown varieties are commonly termed sard, while reddish-orange material is carnelian

Polished tiger’s-eye cabochon

Tiger’s eye, mainly fibrous quartz (SiO₂) pseudomorphically replacing crocidolite; commonly associated with iron oxides

Polished banded chert (likely agate-like chalcedony)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide banding

Rounded river cobble

Likely quartz-rich sandstone or metamorphosed quartzite; exact identification is uncertain from the photograph

Petoskey Stone

Hexagonaria percarinata

Orthoceras Fossil

Orthoceras sp. (Extinct genus of nautiloid cephalopod)

Polished orbicular basalt (likely)

Basalt, a fine-grained mafic volcanic rock; dark circular features may be amygdales or orbicules

Tumbled agate or jasper

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-rich jasper

Polished fossiliferous limestone

Micritic limestone, likely bioclastic/fossiliferous calcite (CaCO₃)

Polished agate/chalcedony pebble

Microcrystalline quartz (SiO₂), likely brecciated or mossy agate

Petoskey Stone

Hexagonaria percarinata

Chalk (Sedimentary Limestone)

Calcite (CaCO3)

Rounded gray river pebble

Likely quartz-rich metamorphic or igneous pebble; exact identification requires testing

Dyed agate (likely dyed chalcedony)

Microcrystalline quartz, SiO₂ (chalcedony/agate)

Tumbled gneiss or granitic gneiss pebble

Quartz–feldspar–mica gneiss; composition typically quartz, plagioclase/alkali feldspar, and biotite or hornblende

Polished banded river stone

Likely foliated gneiss or banded metamorphic rock; exact identification requires a fresh surface or testing

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Muscovite Mica

Muscovite KAl2(AlSi3O10)(OH)2

Sandstone

Arenite (primarily Quartz, SiO2)

Slate

Foliated Metamorphic Rock

Graphitic schist

Graphite-rich pelitic schist; primarily quartz, mica, and graphite

Quartz with Mica (Schist/Pegmatite fragment)

Silicon Dioxide (SiO2) with Phyllosilicates (KAl2(AlSi3O10)(OH)2)

Pyrite

Iron Disulfide (FeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Quartz River Cobble

Silicon Dioxide (SiO2)

Chalk

CaCO3 (Calcium Carbonate)

Petoskey Stone

Hexagonaria percarinata

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Tumbled agate or chalcedony

Microcrystalline quartz, SiO₂; likely banded chalcedony/agate

Pyrite

Iron sulfide (FeS2)