Organic (Paper And Cellulose)

Polished orbicular stone, likely granite or diorite

Granite–diorite, composed mainly of feldspar, quartz, and dark amphibole/biotite

White Marble

Recrystallized Calcite (CaCO3)

Tumbled orbicular granite

Granite, predominantly potassium feldspar, plagioclase, quartz, and biotite/hornblende

Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Polished black stone sphere (likely black basalt or black tourmaline)

Most likely fine-grained basalt (plagioclase–pyroxene); mineral identification is uncertain from the image alone

Tumbled orange chalcedony or jasper pebble

Microcrystalline quartz, SiO₂; possibly iron-stained chalcedony/jasper

Polished brown river pebble

Likely quartzite or weathered metabasalt; exact identification requires hardness and streak tests

Rounded reddish-brown river cobble, likely weathered granite or granitic gneiss

Feldspar–quartz–mica rock; exact identification requires a fresh surface or testing

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Rounded river pebble

Probably quartz-rich sandstone or lithic sandstone; exact identification requires testing

Tumbled banded quartzite or jasper

Silica-rich quartzite; likely iron-oxide-stained quartz (SiO₂)

Tumbled fossiliferous limestone

Bioclastic limestone, likely crinoidal or shell-rich limestone (calcite, CaCO₃)

Polished banded jasper

Microcrystalline quartz (SiO₂), commonly with iron-oxide and clay-mineral bands

Bauxite

Bauxite (Al(OH)3 mixed with Fe2O3 and clay minerals)

Quartz-veined Limestone

Sedimentary limestone with hydrothermal quartz/calcite veins (CaCO3 / SiO2)

Polished malachite–agate breccia (likely)

Microcrystalline quartz/chalcedony (SiO₂) with iron-oxide staining; exact identification requires testing

Dark river pebble, likely basalt or fine-grained volcanic rock

Basalt (probable); mostly plagioclase and pyroxene, with possible magnetite

Rounded gray river pebble, likely basalt or andesite

Fine-grained mafic volcanic rock; commonly basalt (plagioclase, pyroxene, and possible olivine)

Raw graphite-rich metamorphic rock (probable graphite schist)

Graphite schist; predominantly crystalline carbon (graphite, C) with mica and quartz

Banded Sandstone (River Cobble)

Arenite Sandstone with heavy mineral layering

Pumice (Vesicular Rhyolite/Andesite)

Pumice (a highly vesicular volcanic glass/extrusive igneous rock)

Muscovite Schist

Muscovite (KAl2(AlSi3O10)(OH)2) in Schist

Likely graphite-rich ore or galena-bearing rock

Graphite (C) or galena (PbS), identification uncertain from photograph

Limestone

Limestone (CaCO3)

Sandstone (Wonderstone)

Arenite (composed primarily of SiO2 with Fe2O3 impurities)

Banded Sandstone

Arenite with Liesegang banding (primarily SiO2 with FeO(OH) impurities)

Kaolinite (Kaolin)

Kaolinite (Al2Si2O5(OH)4)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Polished gray stone pebble

Likely fine-grained basalt or andesite; exact identification is uncertain from the photograph

Rounded quartz-rich pebble

Likely quartzite or granitoid-derived felsic rock; exact identification is uncertain from the image

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Rounded gray river pebble

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

Polished fossil ammonite cross-section

Ammonoidea (extinct cephalopod; commonly Jurassic/Cretaceous ammonite)

Pyrite (Fool's Gold)

Iron Pyrite (FeS2)

Sandstone (with Iron Staining)

Quartz Arenite / Ferruginous Sandstone

Biotite Mica

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

Tumbled orbicular jasper

Orbicular jasper, chiefly microcrystalline quartz (SiO₂) with iron oxides and other silicates

Polished fossiliferous limestone (likely crinoidal or shell-rich limestone)

Bioclastic limestone, primarily calcite (CaCO₃), containing fossil fragments

Weathered river cobble, likely basaltic or andesitic volcanic rock

Fine-grained mafic to intermediate igneous rock; exact identification requires testing

Tumbled agate/chalcedony

Microcrystalline quartz (SiO₂), likely agate or jasper-bearing chalcedony

Polished red jasper (likely brecciated jasper)

Jasper, microcrystalline quartz/chalcedony; primarily SiO₂ with iron-oxide coloring

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2)