Rock (Likely Sedimentary)

Sandstone (likely Arkosic or Quartzose)

Arenite (SiO2 based with mineral inclusions)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Sandstone Beach Pebble

Clastic Sedimentary Rock (primarily Quartz with Iron Oxide coating)

Red Jasper (in Quartz/Chalcedony)

Silicon Dioxide (SiO2) with iron oxide inclusions

Polished Stone Pendant (Identity Unclear)

Unknown (Possibly Jasper/Agate/Quartz mixture)

Chert (and Agate/Quartz in Geode-like Nodule)

Silicon Dioxide (SiO2)

Unidentifiable Specimen

Undetermined

Chert (Jasper variety)

Microcrystalline quartz (SiO2)

Sandstone Concretion with Quartz Center

Sedimentary Clastic Rock (SiO2 matrix with Quartz core)

Sandstone

Arenite (primarily SiO2)

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (Lithic Sandstone)

Foliated Metamorphic Rock (likely Gneiss or Schist)

Gneissic Metamorphic Rock

Chert (River Pebble)

Microcrystalline silicon dioxide (SiO2)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Banded gneiss (weathered glacial erratic)

Gneiss; typically quartz–feldspar–biotite ± hornblende

Iron-stained sandstone or weathered ironstone concretion

Quartz-rich sandstone, locally cemented by iron oxides (hematite/goethite); exact identification requires testing

Shale or Slate with Quartz Veins

Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Quartz-rich river pebble, likely milky quartz

Milky quartz (SiO₂), possibly a quartzite or quartz-rich silicate pebble

Chalcedony (Quartz Nodule)

Silicon Dioxide (SiO2)

Rounded quartz-rich beach pebble

Likely quartzite or quartz-rich sandstone; predominantly quartz (SiO₂)

Banded gneiss (likely amphibolite-rich gneiss)

Banded gneiss; composition commonly quartz, feldspar, mica and/or amphibole

Mixed collection of common river stones

Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material

Sandstone Pebble with Iron Staining

Clastic Sedimentary Rock (primarily Quartz with Fe2O3 oxides)

Chert (Green River Chert)

Microcrystalline Quartz (SiO2)

Gneiss (Cobble)

Gneiss

Rounded chert or chalcedony pebble

Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony

Chert (Arrowhead or Projectile Point)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Gneiss with Quartz Veining

Gneiss (High-grade Regional Metamorphic Rock)

Weathered brown stone, possibly basalt or iron-rich sedimentary rock

Indeterminate from photograph; likely fine-grained mafic rock (basalt) or ferruginous sandstone

Granitic Gneiss

Gneiss (High-grade Metamorphic Rock)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Gneiss (with Quartz and Mica)

Gneiss

Gneiss

Gneiss (High-grade metamorphic rock)

Chert (Common Opal/Agatized Rock)

Microcrystalline Quartz (SiO2) with potential Chalcedony/Opaline silica

Likely weathered river pebble

Indeterminate lithology; possibly fine-grained sandstone, siltstone, or chert

Greenstone / Diabase Porphyry

Porphyritic Diabase (Micro-gabbro)

Granite (likely biotite granite)

Coarse-grained felsic plutonic rock: quartz + feldspar + biotite; approximate composition SiO₂-rich

Red Sandstone

Arenite (Ferruginous Sandstone)

Sandstone (likely Quartzite-rich)

Arenite (primarily SiO2)

Quartz Veined Rock (Likely Graywacke or Quartzite)

Silicon Dioxide (SiO2) veins in Metasedimentary matrix

Weathered iron-rich rock, possibly laterite or limonite-bearing sandstone

Laterite/limonite-rich material; commonly dominated by goethite (FeO(OH)) and hydrated iron oxides