Organic (Paper And Cellulose)

Polished agate or jasper pebble

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-oxide-bearing

Polished/tumbled brown stone, likely brown jasper or chert

Microcrystalline quartz (SiO₂), probably jasper/chert; exact identification requires testing

Polished agate/geode fragment

Microcrystalline quartz (chalcedony), SiO₂, with possible calcite or quartz cavity lining

Tumbled agate or chalcedony

Microcrystalline quartz (SiO₂), likely agate/chalcedony

Banded ironstone pebble

Jasper-rich iron formation; chiefly microcrystalline quartz (SiO₂) with iron oxides/hydroxides

Tumbled brown jasper

Microcrystalline quartz/chalcedony (SiO₂), likely iron-stained jasper

Likely tumbled jasper or agate

Microcrystalline quartz (SiO₂), possibly iron-rich jasper

Tumbled reddish-brown stone, possibly jasper or iron-rich quartzite

Uncertain from image; likely microcrystalline quartz (SiO₂) with iron-oxide inclusions

Tumbled pink banded agate

Chalcedony (microcrystalline quartz, SiO₂), an agate variety

Tumbled jasper or rhyolitic volcanic rock

Microcrystalline quartz-bearing rhyolite/jasper; commonly quartz (SiO₂), feldspar, and iron-oxide minerals

Septarian Nodule

Septarian concretion (composition: Calcium carbonate, Aragonite, and Siderite/Baryte)

Petoskey Stone (Fossilized Rugose Coral)

Hexagonaria percarinata

Polished septarian nodule

Calcite–aragonite–barite septarian concretion, commonly in a claystone or limestone matrix

Polished/tumbled septarian nodule (likely)

Calcite–aragonite–barite septarian concretion; composition varies, commonly calcite (CaCO₃) with clay/mudstone and iron oxides

Polished agate/jasper nodule

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide impurities

Tumbled banded metamorphic stone

Likely banded gneiss or migmatitic gneiss; exact identification requires testing

Agate Geode Node

Cryptocrystalline Quartz (SiO2)

Dyed Purple Agate

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Petoskey Stone

Hexagonaria percarinata (Fossilized Rugose Coral)

Dyed Agate Geode

Silicon Dioxide (SiO2) with artificial pigment

Fossilized Coral (Petoskey-like or Favosites)

Anthozoa (Fossilized Coral)

Thunderegg (specifically a Jasper/Agate-filled Geode nodule)

Silicon Dioxide (SiO2) within Rhyolitic Matrix

Rounded weathered stone

Indeterminate; likely a fine-grained mafic rock such as basalt or andesite

Polished fossil coral (likely agatized coral)

Fossilized colonial coral; commonly silicified as chalcedony/quartz (SiO₂)

Tumbled agate or chalcedony

Microcrystalline quartz (SiO₂), likely yellow-brown chalcedony/agate

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Quartzite

Quartzite (SiO2)

Sandstone (River Cobble)

Sandstone (composed predominantly of SiO2 - Quartz)

Sandstone

Sandstone (composed predominantly of Quartz, SiO2)

Biotite on Quartz

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

Sandstone Pebble

Arenite (SiO2 with various cementing agents)

Sandstone

Arenite (primarily SiO2)

Graphite

Graphite (Native Carbon, C)

Fossil fish slab

Fossilized fish remains, likely a laminated shale-hosted vertebrate fossil; exact taxon is indeterminate from the image

Red Sandstone Pebble

Arenite (Quartz Sandstone / Hematitic Sandstone)

Tumbled white quartz

Quartz (silicon dioxide, SiO₂), likely milky quartz

Chalk (Limestone)

Calcium Carbonate (CaCO3)

Agate Sliced Nodule

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Orthoceras Fossil in Limestone

Orthoceras regulare (Class Cephalopoda)

Fossil Coral (Favosites)

Favosites sp. (Phylum Cnidaria, Class Anthozoa)