Rock (Likely Sedimentary)

Weathered quartz-rich pebble

Likely altered granite or granitic gneiss; chiefly quartz and feldspar with minor mica/iron oxides

Obsidian

Volcanic Glass (Amorphous Silicon Dioxide)

River Pebble (Likely Quartzite or Gneiss)

Metamorphosed Silicate Rock (primarily SiO2)

River Stone (likely Basalt or fine-grained Andesite)

Extrusive Igneous Rock (Mafic to Intermediate)

Fossilized tooth or tooth fragment

Indeterminate vertebrate tooth; likely mammalian, mineralized hydroxyapatite

Sandstone Concretion

Sedimentary concretion

Sandstone with Quartz Vein

Arenite with Crystalline Silica (SiO2)

Granite Pebble (Salt and Pepper Granite)

Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Biotite/Amphibole)

Chert (Arrowhead/Projectile Point)

Cryptocrystalline Quartz (SiO2)

Porphyritic Basalt

Amygdaloidal Porphyritic Basalt

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitoid; possibly gneiss if the visible layering is tectonic

Smoky Quartz and Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Tumbled dark pebble, likely iron-rich jasper or chert

Jasper/chert, predominantly microcrystalline quartz (SiO₂) with iron-oxide impurities

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Siltstone

Siltstone (composed of clastic quartz and feldspar grains)

Chert (Jasper/Chalcedony variant)

Microcrystalline Quartz (SiO2)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Chert Pebble with Inclusion

Microcrystalline Quartz (SiO2)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Dalmatian jasper (likely orbicular microgranite)

Quartz–feldspar–biotite/pyroxene microgranite; commonly marketed as Dalmatian jasper

Quartzite River Rock

Quartzite (SiO2)

Jasper and Agate (Polished Pebble)

Chalcedony (SiO2 with impurities)

Tumbled dark stone, likely basalt

Basalt (fine-grained mafic volcanic rock; commonly plagioclase, pyroxene, and minor olivine)

Likely basalt (possibly a dark beach pebble)

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

Black basalt (likely polished or cut fragment)

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, clinopyroxene, and often olivine or magnetite

Petrified Wood

Silicified Wood (SiO2)

Quartzite (Beach Pebble)

Quartzite (Composition: SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Banded calcite/aragonite mineral specimen (tentative)

Calcite (CaCO₃), possibly with aragonite or crystalline carbonate growth

Likely porphyritic granite or granitic pegmatite fragment

Quartz–feldspar–mica granitoid; exact identification requires testing

Granite (likely weathered granite or granitic gneiss)

Granite; chiefly quartz (SiO₂), feldspar, and mica

Colorless faceted gemstone, likely cubic zirconia

Cubic zirconia (zirconium dioxide, ZrO₂); visual confirmation is unavailable

Green Aventurine (likely)

Silicon dioxide (SiO2) with fuchsitemica inclusions

Black granite (likely polished gabbro or diabase)

Granitoid rock dominated by feldspar, quartz, and dark mafic minerals; exact identification requires testing

Herkimer Diamond

Quartz (Silica - SiO2)

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Rounded pink granite pebble

Granite, chiefly quartz, alkali feldspar, plagioclase, and minor biotite/hornblende

Tumbled black stone, likely basalt or obsidian

Uncertain; likely fine-grained basalt (plagioclase–pyroxene) or dark volcanic glass (obsidian)

White marble (likely calcitic marble)

Calcite-rich marble; primarily calcium carbonate, CaCO₃