Sedimentary Or Igneous Fragment

Rounded river pebble

Indeterminate; likely quartz-rich sandstone, chert, or weathered volcanic rock

Quartz Pebble

Silicon Dioxide (SiO2)

Asphalt Conglomerate

Artificial Bituminous Conglomerate

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Ooids (Oolites)

Ooids (composed of Calcium Carbonate / CaCO3)

Quartz (Citrine or Iron-Stained variety)

Silicon Dioxide (SiO2)

Quartz

SiO2 (Silicon Dioxide)

Likely granite or granitic gneiss

Quartz–feldspar–mica aggregate; possibly foliated granitic gneiss

Greenstone / altered basalt fragment

Likely chlorite–epidote–actinolite altered basalt; exact identification requires testing

Likely weathered brown quartz-bearing rock

Tentatively weathered granite or granitic gneiss; exact identification is uncertain from the photograph

Weathered quartz-rich rock, possibly granite or pegmatite fragment

Uncertain; likely quartz–feldspar aggregate, potentially granitic pegmatite

Chert (specifically Chalcedony/Flint variant)

Silicon Dioxide (SiO2)

Possible iron-rich basalt or industrial slag

Basalt, likely Fe–Mg silicate rock; exact identification is uncertain from the blurred image

Likely fossilized shell or carbonate concretion

Indeterminate biogenic calcium carbonate, commonly calcite (CaCO₃)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Common Gravel / Pebble

Lithified rock fragment / Detrital sediment

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Likely basaltic rock fragment

Fine-grained mafic igneous rock, probably basalt (plagioclase–pyroxene ± olivine)

Obsidian arrowhead

Volcanic glass (predominantly rhyolitic SiO₂)

Tooth or shell fragment (likely fossilized marine material)

Indeterminate; possibly a fossil fish tooth or mollusk shell fragment composed mainly of calcium carbonate (CaCO₃)

Chert (Arrowhead Fragment)

Silicon Dioxide (SiO2)

River Cobble (Quartzite or Sandstone)

Clastic sedimentary rock (primarily SiO2)

Coquina or Fossiliferous Sandstone

Fossiliferous Calcarenite (CaCO3 with SiO2 inclusions)

Brecciated jasper or brecciated chert

Silica-rich breccia, chiefly microcrystalline quartz (SiO₂), with iron-oxide staining

Sandstone Chert/Quartzite

Silicon Dioxide (SiO2) - Sedimentary Sandstone / Orthoquartzite

Quartz / Common Opal Transition

Silicon Dioxide (SiO2)

Chert (Arrowhead Fragment)

Microcrystalline Quartz (SiO2)

Weathered basalt or iron-rich volcanic rock

Fine-grained mafic igneous rock, likely basalt; exact identification requires testing

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Rosy/Clear variety)

Silicon Dioxide (SiO2)

Likely weathered gray stone or chert fragment

Uncertain; possibly microcrystalline quartz (SiO₂)-rich chert

Clear Quartz

Silicon Dioxide (SiO2)

Basalt and weathered granite-like rock

Dark specimen: basalt, likely vesicular or fine-grained mafic volcanic rock; tan specimen: uncertain, possibly weathered granite or iron-stained felsic rock

Concrete Fragment

Hardened Portland cement and mineral aggregate

Likely basalt fragment

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine

Iron Meteorite (Fragment)

Siderite (Iron-Nickel alloy: Kamacite and Taenite)

Iron Meteorite Fragment

Siderite (Geological term for iron meteorite class - Fe/Ni alloy)

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (silicon dioxide, SiO₂); if granular and foliated, likely quartzite

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Fossilized Tooth Fragment

Vertebrate Fossil (Mammalia indet.)