Sedimentary Or Igneous Fragment

Granite-like pebble

Likely granitic rock, composed mainly of quartz, feldspar, and mica

Quartz pebble

Silicon dioxide (SiO2)

Possible weathered basalt or slag fragment

Basalt, chiefly plagioclase and pyroxene; identification is uncertain from the image

Weathered granitic rock fragment

Likely granite or granodiorite; quartz–feldspar–mica aggregate

Unidentified small rocks or gravel

Worn granitic or quartz-rich rock fragment

Likely granite or granitic gneiss; exact identification requires a fresh surface and testing

Likely calcite-bearing limestone

Calcite (CaCO₃), probably in a porous limestone fragment

Pale greenish quartz-bearing rock, possibly serpentine or altered feldspar

Tentatively serpentinite-related rock (serpentine-group minerals) or altered granitic material; identification is uncertain from the photograph

Weathered granite (likely with accessory quartz)

Granite; chiefly quartz, K-feldspar, plagioclase, and biotite/hornblende

Basalt Pebble

Extrusive Igneous Rock

Chert (Arrowhead Fragment)

Silicon Dioxide (SiO2)

Milky quartz (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Likely weathered granite or granitic gneiss

Granite; mainly quartz, feldspar, and minor mica/amphibole

Weathered sandstone or granitic rock fragment

Indeterminate siliciclastic rock; likely quartz–feldspar–mica aggregate

Rounded dark river pebble

Likely basalt or fine-grained andesite; exact identification requires testing

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially granitic or quartzitic material

Clear Quartz

Silicon Dioxide (SiO2)

Banded Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica)

Iron-rich reddish rock, possibly weathered basalt or ironstone

Indeterminate; likely oxidized mafic rock containing iron oxides and silicate minerals

Sandstone (with concrete/human-made layer)

Clastic Sedimentary Rock (primarily Quartz/Feldspar grains)

Granite-like felsic rock

Likely weathered granite or granitic gneiss; predominantly quartz, feldspar, and minor mica

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Rounded quartz-rich pebble

Likely microcrystalline quartz (chalcedony), possibly a weathered quartz or feldspar pebble

Citrine Geode Fragment

Silicon Dioxide (SiO2) with iron impurities

K-Feldspar Granite Fragment

Felsic Plutonic Rock (Granite)

Quartz Pebble

Silicon Dioxide (SiO2)

Small quartz-rich pebble, possibly milky quartz

Quartz (silicon dioxide, SiO₂)

Milky quartz (likely iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Quartz-rich stone fragment (probable quartzite or chert)

Quartzite, composed predominantly of SiO₂; exact identification is uncertain from the image

Weathered, iron-stained rock fragment

Unidentified iron-oxide-stained silicate rock; precise identification is not possible from the image

Weathered quartz-bearing rock fragment

Indeterminate; likely quartz-rich granite, gneiss, or pegmatitic rock

Weathered quartz-rich rock fragment

Indeterminate; likely altered granite or quartz-bearing pegmatite

Polished fossiliferous limestone

Bioclastic limestone, commonly fossil-rich micrite or wackestone

Quartz (likely) / Siliceous rock with quartz phenocrysts (if a rock fragment)

Quartz (SiO₂)

Small rounded limestone pebble

Limestone, predominantly calcite (CaCO₃), possibly fossiliferous or oolitic

Fossiliferous Shale

Laminated Mudrock with plant fossils

Weathered brown rock fragment

Indeterminate; possibly weathered granite, gneiss, or iron-stained quartz-rich rock

Likely weathered sandstone or iron-stained sedimentary fragment

Quartz-rich sandstone; exact identification requires testing

Concretion

Sedimentary Concretion (Ironstone / Calcite Concretion)

Conglomeratic breccia (polymict volcanic breccia)

Polymict volcaniclastic breccia; clasts likely basaltic/andesitic rock in a dark matrix

Fossiliferous Limestone or Mudstone

Sedimentary Rock with Invertebrate Fossils

Small rounded pebble, likely limestone or quartz-rich sedimentary fragment

Indeterminate lithic clast; probable micritic limestone (CaCO₃) or weathered quartz-rich stone