Not A Rock Or Mineral

Quartz-rich rock, likely granite or quartz-bearing metamorphic rock

Undetermined; possibly granitic rock composed mainly of quartz and feldspar, with mica or other dark minerals

Unidentified gray mineral/rock fragment

Indeterminate from the photograph; possibly a quartz- or feldspar-bearing rock fragment

Shale

Laminated Mudstone (Shale)

Red Sandstone

Sedimentary Litharenite / Quartz Arenite

Weathered granite (probable)

Granite; a coarse-grained rock composed chiefly of quartz, feldspar, and mica

Weathered granite

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspars, and mica

Desert Rose

Gypsum (CaSO4·2H2O) or Barite (BaSO4)

Greenstone (likely chlorite- or epidote-rich metamorphic rock)

Greenstone; commonly metamorphosed basalt or dolerite, with chlorite, epidote, and actinolite

River Rock / Stream Pebble

Fluvial Clast / Rounded Sedimentary Particle

Smooth river pebble (exact rock type indeterminate)

Unidentified rounded lithic clast; composition cannot be determined from the photograph

Rhyolite

Extrusive felsic igneous rock

Small water-worn pebble, likely granite or granitic rock

Granite (tentative; exact identification is uncertain from the photo)

Quartz (Druzy) in host rock

SiO₂ (Silicon Dioxide) as Quartz, with unspecified host rock components (likely silicates and iron oxides)

Gravel or Crushed Stone

Fragmented Aggregate Stone

Quartz with Mafic/Chlorite Veins

Silicon Dioxide (SiO2) with Chlorite/Epidote cross-veining

Granite

Felsic intrusive igneous rock

Pegmatite with Tourmaline

Pegmatite / Silicate

Granite

Felsic intrusive igneous rock

Granite Pebble

Intrusive Igneous Rock

Gravel and Sand Mixture

Unconsolidated clastic sediment

Weathered greenstone (altered mafic rock)

Greenschist-facies metabasalt; typically chlorite, actinolite, epidote, and albite

Likely weathered granite or granitic gneiss

Granite: quartz + feldspar + mica; possibly gneiss if the faint texture reflects foliation

Weathered Sedimentary Rock

Sedimentary Rock

Agate Geode

Silicon Dioxide (SiO2) - Chalcedony variety

Small rounded pebble

Unidentified lithic pebble; composition cannot be determined from the image

Desert Rose (Baryte or Selenite variant)

Barium Sulfate (BaSO4) or Gypsum (CaSO4·2H2O) with Sand inclusions

Rounded brown pebble (rock type undetermined)

Unidentified, iron-stained lithic pebble; composition cannot be determined from the photograph

Yellow Agate (Banded Chalcedony)

Silicon Dioxide (SiO2)

Polished dark-speckled igneous pebble, likely diorite or gabbro

Probable diorite (plagioclase feldspar and hornblende/biotite); exact identification is uncertain from the image

Small tan mineral or rock fragment (unidentified)

Indeterminate from the image; no diagnostic features are visible

Weathered iron-rich rock, possibly limonite-bearing basalt or laterite

Indeterminate; likely Fe-oxide/hydroxide–altered mafic rock, dominated by limonite/goethite with silicate minerals

Sandstone

Clastic Sedimentary Rock

Weathered granite pebble

Granite, a quartz–feldspar–mica intrusive rock

Sandstone

Clastic sedimentary rock

Weathered iron-stained rock fragment

Uncertain from the image; likely an iron-oxide-stained, quartz- and feldspar-bearing rock

Granite

Felsic intrusive igneous rock

Serpentinite (probable)

Serpentinite, a rock composed chiefly of serpentine-group minerals such as antigorite, lizardite, or chrysotile

Green serpentine-rich rock (possibly serpentinite)

Serpentinite, composed chiefly of serpentine-group minerals (e.g., lizardite, antigorite, or chrysotile)

Dark gray fine-grained rock fragment

Possibly andesite or basalt; exact identification is not possible from the image alone

Granite and Basalt Specimen

Plutonic and Volcanic Igneous Rocks

Weathered volcanic rock, likely andesite or basaltic-andesite

Fine-grained plagioclase–pyroxene volcanic rock; possible altered andesite (exact identification requires testing)

Fossil-bearing limestone with a likely fossil shell

Bioclastic limestone, chiefly calcite (CaCO₃); fossil identity uncertain from the photo