Industrial Byproduct (Anthropogenic Rock)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered iron-rich rock fragment

Likely limonite/goethite with hematite and iron-bearing silicates; exact identification requires testing

Basalt

Aphanitic Mafic Volcanic Rock (Fe/Mg rich)

Basalt pebble

Basalt

Small gray, fine-grained pebble (possibly a weathered sandstone or siltstone)

Unidentified lithic pebble; composition cannot be determined from the image

Serpentine

Serpentine group ((Mg,Fe,Ni,Al,Zn,Mn)3(Si,Al)2O5(OH)4)

Small, pale gray-green rock fragment

Undetermined fine-grained silicate rock; exact identification is not possible from the image

Basalt

Extrusive mafic igneous rock

Weathered quartz-rich rock fragment

Indeterminate; likely quartz-bearing granitoid or quartzite

Granite Pegmatite

Felsic intrusive igneous rock

River Stone (Basalt)

Extrusive Igneous Rock (Mafic)

Limestone

Sedimentary Rock (Primarily CaCO3)

Rounded pebble, likely quartz-rich river or beach pebble

Unidentified lithic clast; possibly quartzite or iron-stained quartz-rich rock

Small rock fragments; likely mixed local gravel, not identifiable to one species

Unidentified lithic fragments; individual rock types cannot be determined reliably from this photograph

Kimberlite with Diamonds

Kimberlite (ultramafic potassic igneous rock)

Rounded river pebble (likely weathered granite or metamorphic rock)

Indeterminate; possible granitic or quartz-rich lithology

Garnet in Host Rock

Garnet Group (A3B2(SiO4)3)

Dark rock fragment, possibly basalt

Undetermined; possibly basalt (fine-grained mafic volcanic rock)

Small rounded pebble, likely quartz-rich rock

Unidentified silicate-rich pebble; possibly granitic or quartzitic

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Ironstone (Limonitic Shale)

Ferruginous Siltstone / Goethite-rich Sedimentary Rock

Weathered pebble, possibly quartz-rich river stone

Unidentified silicate rock; composition cannot be determined reliably from the image

Milky quartz pebble

Quartz, SiO₂ (microcrystalline to crystalline variety)

Dark pebble with pale mineral patches

Likely porphyritic basalt or andesite; identification is uncertain from the photograph

Tumbled yellow chalcedony (possibly citrine or pale agate)

Chalcedony, microcrystalline quartz (SiO₂); exact variety cannot be confirmed visually

Sandstone

Arenite

Rounded pebble, likely mixed lithology

Lithology uncertain; possibly a fine-grained metamorphic or volcanic rock with a quartz-rich/pink feldspar vein or inclusion

Eclogite

Eclogite (Omphacite-Garnet Metamorphic Rock)

Sandstone

Arenite (composed mainly of SiO2)

Sandstone (Quartz-rich)

Arenite (primarily SiO2)

Likely small iron-rich concretion or weathered mineral fragment

Indeterminate; possibly limonite/goethite-bearing material with quartz or feldspar

Milky quartz in dark host rock

Quartz (SiO₂), likely as a vein or vein fragment; host rock uncertain

Vesicular Basalt or Scoria

Basalt (extrusive volcanic rock)

Quartz (Tumbled)

Silicon Dioxide (SiO2)

Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Small polished, cream-colored stone (possibly quartz or marble)

Unidentified; appearance alone cannot distinguish quartz (SiO₂) from calcite-rich marble (CaCO₃) or another pale stone

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Basalt

Basalt (Aphanitic Mafic Volcanic Rock)

Basalt (Vesicular/Scoria)

Vesicular Basalt

Basalt

Basalt (Aphanitic Mafic Igneous Rock)