Organic (Paper And Cellulose)

Petoskey Stone (Fossilized Rugose Coral)

Hexagonaria percarinata

Quartzite River Cobble

Quartzite (dominated by SiO2)

Marble

Metamorphosed Limestone (principally CaCO3)

Weathered iron-rich rock, possibly ironstone or altered basalt

Indeterminate; likely ferruginous basalt/ironstone containing hematite-goethite and silicate minerals

Tumbled brown agate or jasper

Microcrystalline quartz, SiO₂, likely chalcedony with iron-oxide inclusions

Amethyst geode

Quartz (SiO₂), purple variety colored mainly by iron and irradiation

Polished septarian nodule

Septarian concretion, commonly calcite-filled cracks in a claystone or limestone matrix

Tumbled agate (likely Botswana or fortification agate)

Microcrystalline quartz, SiO₂ (chalcedony with banded impurities)

Rounded granite cobble

Granite; predominantly quartz, alkali feldspar, plagioclase, and mica

Tumbled banded agate

Agate, microcrystalline chalcedony (SiO₂)

Tumbled banded stone, likely gneiss or granite

Quartz–feldspar rock, possibly banded gneiss; exact identification requires testing

Polished/tumbled agate or jasper

Cryptocrystalline quartz, SiO₂; likely mossy or dendritic agate/jasper variety

Polished basalt or basaltic river pebble

Basalt; fine-grained plagioclase–pyroxene rock, possibly containing olivine

Polished brecciated jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), with iron-oxide-rich breccia fragments and cement

Red jasper pebble

Microcrystalline quartz (SiO₂), colored chiefly by iron oxides

Limestone

Sedimentary Rock (Primarily Calcite: CaCO3)

Porphyritic Diabase (Porphyry)

Porphyritic Diabase / Microgabbro

Polished/tumbled brown jasper or brecciated jasper

Microcrystalline quartz (SiO₂), commonly including hematite, iron oxides, and assorted silicified fragments

Banded Gneiss

Gneiss (quartz-feldspar-biotite metamorphic rock)

Puddingstone (Conglomerate)

Conglomerate (clastic sedimentary rock)

Blue agate slice

Microcrystalline quartz (chalcedony), SiO₂, commonly colored blue by dyes or inclusions

Tumbled brown agate/chalcedony (probable)

Microcrystalline quartz, SiO₂; likely iron-stained agate or jasper

Polished porphyritic volcanic pebble

Likely porphyritic basalt or andesite; exact identification requires a fresh surface and mineral tests

Graphite-rich schist (probable)

Graphite schist; primarily graphite (C) with mica and quartz

Muscovite Mica

Muscovite - KAl2(AlSi3O10)(F,OH)2

Biotite-bearing metamorphic rock, likely schist

Mica schist; chiefly quartz, feldspar, and biotite mica

Calcite

Calcium Carbonate (CaCO3)

Muscovite Mica

Muscovite: KAl2(AlSi3O10)(OH)2

Almandine Garnet

Almandine, Fe3Al2(SiO4)3

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Tumbled white quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Pyrite

Iron Sulfide (FeS2)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Calcite

Calcium Carbonate (CaCO3)

Rounded river cobble, likely weathered sandstone or quartz-rich metasandstone

Indeterminate sandstone; commonly quartz (SiO₂) with feldspar, lithic grains, and iron-oxide cement

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Tumbled black stone, likely basalt or black jasper

Basalt (fine-grained plagioclase–pyroxene rock), possibly opaque microcrystalline quartz/jasper

Talc

Talc (Hydrated magnesium silicate, Mg3Si4O10(OH)2)

Polished gray pebble, likely quartzite or fine-grained granite

Probable quartzite (mostly microcrystalline SiO₂); identification is uncertain from the photograph

Jasper (specifically Owyhee or Picture Jasper variety)

Jasper (Silicon Dioxide, SiO2)