Sedimentary (Base), Then Artificial

Conglomerate

Conglomerate (clastic sedimentary rock)

Gneiss

Gneiss (SiO2-rich metamorphic rock)

River Stone (Quartzite/Siltstone mixture)

Silicon Dioxide (SiO2) based metamorphosed sandstone

Sandstone

Arenite (SiO2 primarily)

Fossiliferous Limestone

Sedimentary Calcium Carbonate (CaCO3)

Sandstone

Arenite (SiO2 based with mineral cement)

Limonite/Goethite on Shale

Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock

Mica

Mica group (often Muscovite or Biotite)

Conglomerate

Clastic Sedimentary Conglomerate (SiO2 based clasts in matrix)

Limestone Riprap

Sedimentary Calcium Carbonate (CaCO3)

Sandstone

Arenite (SiO2 based typically)

Agate

Agate (a variety of Chalcedony, SiO2)

Granite Gneiss

Gneiss (containing quartz, alkali feldspar, plagioclase, biotite/amphibole)

Gneiss

Gneiss (Metamorphic rock composed primarily of quartz, feldspar, and mica)

Limestone (specifically a Crushed Aggregate fragment)

Calcium Carbonate (CaCO3)

Smooth gray river pebble

Likely fine-grained sandstone or siltstone; exact identification requires a fresh surface and tests

Grey River Pebble (Likely Quartz-rich or Limestone)

Clastic Sedimentary Rock (typically SiO2 or CaCO3 based)

Ironstone (Limonite/Hematite)

Ferruginous Sedimentary Rock (composed largely of Fe2O3 and FeO(OH)·nH2O)

Chert Arrowhead (Flint Projectile Point)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

River Pebble Gravel

Hydrothermally modified Clastic Sediment (mainly Quartzite and Chert)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Sandstone (Limonitic/Arkose)

Sandstone (primarily SiO2 with FeO(OH)·nH2O)

Limestone Cobble

Sedimentary Limestone (Calcium Carbonate, CaCO3)

Limestone (Weathered Aggregate)

Sedimentary Carbonate Rock (CaCO3)

Chert (River Siltstone/Quartzite)

Sedimentary Cryptocrystalline Quartz (SiO2)

Chert (Arrowhead/Projectile Point)

Microcrystalline Quartz (SiO2)

Dragon Blood Jasper

Epidote with Red Piedmontite (Chalcedony/Quartz variant)

Zoisite with Hornblende

Zoisite (Ca2Al3(SiO4)3(OH)) with Amphibole inclusions

Conglomerate

Clastic Sedimentary Rock

Banded River Stone (Greywacke or Siltstone subtype)

Sedimentary Banded Siltstone

Conglomerate (or Breccia)

Clastic Sedimentary Rock

Sandstone (likely Graywacke or Lithic Sandstone)

Clastic Sedimentary Rock

Limestone (Weathered / Limonite-stained)

Sedimentary carbonate rock (CaCO3)

Limestone

Sedimentary Rock (Primarily CaCO3)

Conglomerate

Clastic Sedimentary Rock (Conglomerate)

Conglomerate

Conglomerate (Clastic sedimentary rock)

Conglomerate

Conglomerate (clastic sedimentary rock)

Sandstone (lithic)

Lithic Wacke / Arenite

Gneiss

Gneiss

Chert

Microcrystalline silica (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Banded Gneiss

Gneiss (Felsic to Mafic Metamorphic Rock)