Mixed

Weathered quartz-bearing rock fragment

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

Rounded quartz-rich river pebbles

Alluvial gravel; commonly quartzite, chert, and quartz-bearing sandstone fragments

Conglomerate

Polymictic conglomerate; clast-bearing sedimentary rock cemented by silica, calcite, or iron oxides

Weathered volcanic rock fragment

Likely andesite or basaltic-andesite; exact identification requires fresh surface and testing

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Quartz-rich metamorphic rock (likely quartzite)

Quartzite, composed mainly of quartz (SiO₂); exact identification is uncertain from the photo

Polished blue-green stone, likely chrysocolla or chrysocolla-bearing chalcedony

Chrysocolla: hydrated copper phyllosilicate, approximately (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O; exact identification requires testing

Unakite

Unakite (Epidotized Granite)

Unakite

Epidotized Granite

Quartz with Iron Staining

Silicon Dioxide (SiO2) with Hematite/Limonite inclusions

Granite (Pink/Potassium Feldspar rich)

Granite (K-feldspar rich intrusive igneous rock)

Agate (Lake Superior Agate variant)

Chalcedony / Silicon Dioxide (SiO2)

Weathered granitic rock

Granite (quartz–feldspar–mica intrusive rock; exact variety uncertain)

Weathered quartz-rich rock, likely vein quartz

Mostly silicon dioxide (SiO₂); exact rock type cannot be confirmed from the photograph

Asphalt aggregate

Human-made bituminous asphalt containing crushed silicate rock aggregate

Mixed small pebbles and mineral grains

Unidentified detrital sediment; likely quartz-, feldspar-, and lithic fragments

Tumbled granite or granitic gneiss

Granite/granitic gneiss, chiefly quartz, feldspar, and dark mica or amphibole

Iron-rich concretion or weathered limonite/goethite nodule

Limonite (hydrous iron oxides), commonly dominated by goethite (FeO(OH))

Asphalt aggregate pavement

Bituminous asphalt concrete containing crushed stone aggregate

Asphalt Conglomerate

Artificial Bituminous Conglomerate

Pink Granite

Phaneritic Felsic Igneous Rock (Rich in K-Feldspar)

Jasper with Quartz

Silicon Dioxide (SiO2) - Chalcedony variety

Concrete with Exposed Aggregate

Anthropogenic conglomerate (Concrete)

Chrysocolla

Hydrated copper silicate (Cu,Al)2H2Si2O5(OH)4·nH2O

Chalcedony Agate / Carnelian nodules in Matrix

SiO2 (Silicon Dioxide) with iron oxide inclusions

Chrysocolla on Matrix

Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4·nH2O

Unakite

Unakite (Epidotized Granite)

Chrysocolla on Matrix

Hydrated copper silicates ((Cu,Al)2H2Si2O5(OH)4·nH2O)

Mixed rough mineral specimens, likely calcite with prehnite/zeolite

Calcite (CaCO₃), with probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂) and/or zeolite-group minerals

Rounded granitic pebble (likely granite or granodiorite)

Granite–granodiorite; chiefly quartz, feldspar, and mica/amphibole

Conglomerate

Polymictic conglomerate, likely carbonate-cemented

Mixed polished gemstone bead bracelet, likely ocean jasper, agate, and quartz varieties

Mostly microcrystalline quartz (SiO₂), with possible chalcedony, jasper, and minor feldspar or other inclusions

Weathered granitic gneiss (probable)

Gneiss, chiefly quartz–feldspar–biotite; compositionally granitic

Tumbled yellow-brown quartzite or jasper

Quartzite, predominantly microcrystalline quartz (SiO₂), possibly iron-stained jasper

Mixed River Stones and Agates

Mixed Silicates and Ironstones (primarily SiO2 and Fe2O3)

Polymict conglomerate (pebble conglomerate)

Clastic sedimentary rock; rounded pebble and granule clasts in a finer-grained matrix

Likely weathered granite or granitic rock

Granite; quartz + feldspar + mica, compositionally variable

Tumbled brown-black stone, likely smoky quartz or iron-stained agate

Indeterminate from image; possible quartz (SiO₂), chalcedony, or iron-rich jasper

Granite pebble

Coarse-grained granitic rock, primarily quartz–feldspar–biotite

African Turquoise

African Turquoise (a trade name for Jasper, a variety of Chalcedony: SiO2)

Granodiorite

Intermediate Phaneritic Plutonic Rock

Granite

Granite (Felsic Plutonic Rock)