Rock (Likely Sedimentary)

Sandstone

Arenite (Siliclastic sedimentary rock)

Chert (Jasper/Agate mix)

Microcrystalline Quartz (SiO2)

Sandstone

Arenite (primarily SiO2)

Gneiss (Green Gneiss)

Gneiss (High-grade Regional Metamorphic Rock)

Sandstone (likely Graywacke or Lithic Sandstone)

Clastic Sedimentary Rock

River Rock (likely Siltstone or fine-grained Sandstone)

Clastic Sedimentary Rock

Rounded dark river pebble

Likely fine-grained basalt or andesite; exact identification requires a fresh surface or tests

Sandstone (likely Arkosic or Ferruginous)

Arenite (SiO2 with iron oxides or feldspar)

Sandstone

Clastic sedimentary rock (primarily Quartz and Feldspar)

Sandstone (Quartz-rich)

Arenite (Quartz Arenite)

Rounded river or beach pebble

Likely quartz-rich sandstone or quartzite; exact identification requires a close-grained view and hardness test

Sandstone (Weathered Coastal Boulder)

Arenite (composed primarily of SiO2)

Sandstone (likely Quartzose)

Arenite

Banded Chert or Agate

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2)

Gneiss (Gneissic Granite)

Gneiss

Gray Limestone Fragment

Limestone (CaCO3)

Vuggy Limestone

Carbonate Sedimentary Rock with Vuggy Porosity (CaCO3)

Sandstone (Quartz Arenite)

Sandstone (SiO2 with possible mineral cements)

Chert Conglomerate (or Breccia)

Sedimentary Clastic Rock (variety: Ferruginous Chert Breccia)

Sandstone with Manganese Dendrites

Clastic Sedimentary Rock (SiO2 based with MnO2 inclusions)

Rounded river cobble, likely weathered sandstone or siltstone

Quartz-rich clastic sedimentary rock; exact identification requires a fresh surface and testing

Sandstone (Greywacke/Siltstone variant)

Clastic Sedimentary Rock (Lithic Wacke)

Sandstone (Ferruginous)

Arenite (Fe2O3 enriched)

Quartz Geode

Silicon Dioxide (SiO2)

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (SiO2 based)

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Sandstone (Weathered)

Arenite (primarily SiO2)

Chert (often called Jasper or Flint)

Microcrystalline Quartz (SiO2)

Fossil Crab

Decapoda (likely Avitelmessus or Raninidae family)

Weathered River Rock (likely Chert or Basalt with algae)

Silicon dioxide (SiO2) with organic biofilm

Likely pale limestone or calcite-rich rock

Calcite-bearing limestone; chiefly calcium carbonate (CaCO₃)

Sandstone (Weathered Pebble)

Arenite (primarily SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in Calcareous or Siliceous Matrix

Quartzite in Conglomerate

Clastic Sedimentary Rock with Silicon Dioxide (SiO2) inclusions

Chert Nodules in Limestone

Microcrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)

Sandstone (likely with Borings or Vesicular Basalt)

Clastic Sedimentary Rock (Sandstone)

Sandstone-based Concrete Fragment

Cementitious Composite with Sedimentary Aggregate

Likely weathered sandstone fragment

Sandstone, chiefly quartz (SiO₂) with feldspar and iron-oxide cement

Sandstone (likely Arkosic or Lithic)

Clastic Sedimentary Rock (composed predominantly of sand-sized grains, 0.0625 to 2 mm)

Chert (varietal: Flint Pitted Pebble)

Cryptocrystalline Quartz (SiO2)

Sandstone (likely Greywacke or Siltstone variety)

Arenite / Siltstone (primarily SiO2)