Rock (Likely Sedimentary)

Small quartz-rich pebble or rock fragment

Quartz (silicon dioxide, SiO₂), possibly with iron-oxide staining or host-rock inclusions

Sandstone

Arenite (primarily SiO2)

Banded metamorphic rock, likely banded gneiss

Gneiss, probably biotite–quartz–feldspar gneiss

Tumbled limestone or marble

Calcite-rich carbonate rock; likely limestone (CaCO₃), possibly marble

Chert (specifically Agate/Jasper variety)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Ferruginous Chert

Microcrystalline Quartz (SiO2) with Iron Oxides

Weathered mafic rock, likely basalt

Basalt; primarily plagioclase feldspar, clinopyroxene, and commonly olivine or magnetite

Weathered sandstone fragment

Quartz-rich clastic sandstone (tentative)

Porous sandstone or weathered limestone fragment

Indeterminate clastic carbonate/siliciclastic rock; likely quartz-rich sandstone or calcarenite

Quartzite pebble with Mafic inclusions

Quartzite (SiO2)

Weathered granitic cobble

Granitoid, likely granite or granodiorite

Rounded greenish pebble

Indeterminate; likely weathered quartzite, greenstone, or altered volcanic rock

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃)

Weathered limestone or calcitic fossil fragment

Calcite-rich carbonate rock; primarily CaCO₃

Small rounded pebble

Unidentified lithic clast; likely fine-grained sandstone, mudstone, or basalt

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite; composition dominated by mica and quartz

Red Sandstone Pebble

Arenite with iron oxide (Hematite)

Weathered iron-rich concretion or breccia

Goethite/hematite-bearing limonite concretion, possibly ferruginous sandstone

Likely red sandstone or iron-rich volcanic rock

Probable ferruginous sandstone; exact identification requires testing

Rounded gray river cobble

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

Sandstone (Grooved/Weathered)

Arenite (composed primarily of Quartz and Lithic fragments)

Quartz-rich metamorphic rock, likely mica schist or quartzite

Quartz (SiO₂) with probable mica, feldspar, and dark accessory minerals

Rounded granite or granitic gneiss cobble

Granite; primarily quartz, feldspar, and mica (exact identification requires a fresh surface and testing)

Rounded river cobbles, likely weathered sandstone/mudstone and quartz-rich rock

Uncertain from photograph; probable lithologies include quartz sandstone, siltstone/mudstone, and locally altered volcanic or metamorphic clasts

Unidentified weathered rock fragment

Likely limestone or sandstone; exact identification is not possible from the photograph

Petrified Wood

Silicified Wood (primarily SiO2)

Sandstone (likely Arkosic or Lithic)

Clastic Sedimentary Rock (SiO2 with accessory minerals)

Weathered quartz-rich rock, likely sandstone or quartzite

Quartz arenite (sandstone) or quartzite; predominantly SiO₂

Iron-rich concretion or weathered ironstone

Goethite–hematite-rich limonite (FeO(OH)·nH₂O / Fe₂O₃)

Likely garnet-bearing metamorphic rock

Garnet amphibolite or garnet-bearing schist; chiefly almandine garnet (Fe₃Al₂Si₃O₁₂) with amphibole, mica, and quartz

Likely weathered quartz-rich stone or fossil fragment

Indeterminate; possibly quartz-bearing sandstone, iron-stained quartz, or a fragmentary fossil

Weathered brown rock, likely iron-stained sandstone

Quartz-rich sandstone (probable), chiefly SiO₂ with iron-oxide cement

Likely foliated metamorphic rock (schist or gneiss fragment)

Mica schist–gneiss; chiefly quartz, feldspar, and mica

Banded gneiss

Foliated gneiss, likely quartz–feldspar–biotite or amphibole gneiss

Rounded gray pebble

Indeterminate; likely a water-worn silicate or carbonate pebble

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Gneiss (with Mica and Quartz)

Gneissic Metamorphic Rock

Pebble of weathered basalt or andesite

Fine- to medium-grained mafic volcanic rock; commonly plagioclase ± pyroxene, olivine, and iron oxides

Quartz Vein in Host Rock (likely Sandstone or Mudstone)

Silicon Dioxide (SiO2) within Sedimentary Matrix

Rounded river pebble, likely quartz-rich sandstone or weathered granite

Indeterminate lithic clast; probable quartz–feldspar aggregate with iron-oxide staining

Small translucent quartz pebble

Quartz (silicon dioxide, SiO₂), possibly milky or chalcedonic quartz

Unidentified gray metamorphic rock, likely schist or gneiss

Quartz–feldspar–mica metamorphic rock; exact identification requires testing