Rock (Likely Sedimentary)

Chalcedony (Common Agate)

Cryptocrystalline Quartz (SiO2)

Geode or Concretion

Silica-filled nodule (likely SiO2)

Biotite (Black Mica)

Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2

Unidentified Dark Mineral or Rock

Indeterminate (Likely Silicon Dioxide or Carbon-based)

Sandstone (Ferruginous)

Arenite (Fe2O3 rich)

River Pebble (Quartz/Jasper)

Silicon Dioxide (SiO2)

Sandstone (with potential fossil inclusions)

Clastic sedimentary rock (primarily SiO2)

Weathered brown pebble, possibly basalt or iron-rich chert

Provisional identification: fine-grained basalt (plagioclase–pyroxene), potentially coated by iron oxides; exact identification requires testing

Small weathered rock fragment

Indeterminate; possibly limestone or altered volcanic rock

Feldspar-rich granite or granitic gneiss

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

Quartz vein in weathered host rock

Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix

Red jasper in gray host rock (likely hematite-stained quartzite or rhyolite)

Jasper: microcrystalline quartz (SiO₂), with iron-oxide coloration; exact host uncertain from image

Sandstone (likely with Borings or Vesicular Basalt)

Clastic Sedimentary Rock (Sandstone)

Sandstone (Ferruginous)

Arenite with Iron Oxide matrix

Quartz-bearing dark rock, possibly hornfels or basalt

Probable quartz–feldspar rock; exact identification requires testing

Weathered brown stone, possibly chert or iron-stained limestone

Uncertain; likely microcrystalline quartz (SiO₂) chert or calcitic limestone (CaCO₃)

Rounded river cobble, likely weathered sandstone or quartzite

Indeterminate clastic silicate rock; possibly quartz-rich sandstone (SiO₂-dominant)

Chalcedony (Jasper/Agate mix)

Quartz (microcrystalline SiO2)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Iron-stained weathered stone (tentative)

Undetermined; possibly weathered iron-rich basalt or concretion

Fossilized Sea Urchin (Echinoid)

Echinoidea (Class) - likely replaced by Calcite or Quartz

Foliated metamorphic rock, likely gneiss or mica schist

Quartz–feldspar–mica metamorphic rock; exact identification is uncertain from the photograph

Banded sandstone pebble

Quartz-rich sandstone, likely arkosic or ferruginous sandstone

Weathered sandstone or graywacke fragment

Clastic sedimentary rock, likely quartz–feldspar sandstone (exact identification requires testing)

Sandstone (likely Arkose)

Arenite (composed mainly of SiO2 with Feldspar)

Weathered Sandstone with Algae Growth

Arenite

Gneiss (specifically Granitic Gneiss)

Gneissic Metamorphic Rock

Weathered rock fragment (likely granite or quartz-rich sandstone)

Uncertain; possible granitic fragment containing quartz and feldspar

Sandstone (with minor weathering/pitting)

Clastic Sedimentary Rock (composed mostly of SiO2)

Unidentified light-colored rock or mineral specimen

Indeterminate; possibly weathered calcite-rich material, limestone, or pale quartz-bearing rock

Sandstone (Quartzose)

Arenite (primarily SiO2)

Fragmented Sedimentary Pebble

Clastic Sedimentary Specimen

Fossiliferous Limestone Pebble

Biogenic Sedimentary Rock (CaCO3)

Pebble (Likely Basalt or Siltstone)

Clastic sedimentary rock or mafic volcanic rock

Sandstone

Arenite (primarily Quartz-rich)

Weathered brown rock, likely sandstone or iron-rich sedimentary stone

Indeterminate siliciclastic rock; likely quartz-rich sandstone with iron-oxide cement

Weathered basalt or volcanic breccia

Fine-grained mafic volcanic rock, likely basalt (plagioclase–pyroxene ± olivine), possibly brecciated

River Quartzite Siltstone

Quartz-rich Meta-siltstone (SiO2 dominated)

Porphyritic granite (likely orbicular/porphyritic granitoid)

Quartz–feldspar granitoid; commonly composed of K-feldspar, plagioclase, quartz, and biotite/hornblende

Chert (River Pebble)

Cryptocrystalline Quartz (SiO2)

Weathered granite or granitic gneiss block

Granite, chiefly quartz, feldspar, and mica; possibly gneiss if the visible banding is structural

Tumbled cream-colored stone, possibly quartz or calcite

Indeterminate from photograph; likely microcrystalline quartz (SiO₂) or calcite (CaCO₃)