This Is Not A Rock Or Mineral

Basalt with Vesicular Amygdule

Extrusive igneous rock (Mafic)

Quartzite Pebble (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Red Granite Pebble

Intrusive Felsic Igneous Rock (Granite)

Quartz Geode

Silicon Dioxide (SiO2)

Jasper with Purple Fluorite or Chalcedony

Silicon Dioxide (SiO2) with mineral inclusions

Slickenside

Tectonic Fault Scarp Surface

Weathered granite (likely pink biotite granite)

Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Rough turquoise-bearing rock (probable turquoise matrix)

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, likely in a host-rock matrix

Granite

Intrusive Igneous Rock

Orbicular jasper

Siliceous microcrystalline quartz (chalcedony), commonly sold as ocean jasper

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz with Chlorite inclusions

SiO2 with (Mg,Fe)3(Si,Al)4O10(OH)2⋅(Mg,Fe)3(OH)6

Auriferous Quartz (Gold-bearing Quartz)

Silicon Dioxide (SiO2) with trace Gold (Au) and Iron Oxides

Granite

Granite, a coarse-grained felsic intrusive igneous rock composed chiefly of quartz, feldspar, and mica

Sandstone

Arenite (clastic sedimentary rock)

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Quartz-veined Granite or Gneiss Pebble

Silicate-rich metamorphic rock fragment

Turquoise

CuAl6(PO4)4(OH)8·4H2O (Hydrous phosphate of copper and aluminum)

Greenish altered rock, possibly serpentinite or chlorite-rich schist

Tentative: serpentine-group minerals, chiefly antigorite/lizardite, or chlorite–actinolite assemblage

Gneiss, likely migmatitic or granitic gneiss

Banded quartz–feldspar–mica gneiss; composition chiefly quartz, alkali/plagioclase feldspar, biotite and accessory minerals

Quartz Vein Rock

Silicon dioxide (SiO2) within a host rock matrix

Sandstone (Ferruginous)

Arenite (SiO2 with iron oxide impurities)

Pebble (Likely Basalt or Siltstone)

Clastic sedimentary rock or mafic volcanic rock

Spessartine Garnet in Quartz/Feldspar Pegmatite

Spessartine (Mn3Al2(SiO4)3) in Quartz (SiO2) and Feldspar

Iron-stained quartz-rich rock (possibly ironstone or ochre-coated quartz)

Undetermined ferruginous rock; yellow-brown coloration likely from goethite and/or limonite (hydrated iron oxides)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Likely quartz-bearing rock fragment

Quartz (SiO₂), possibly with iron-oxide staining or other mineral inclusions

Likely quartz-rich rocks

Possibly massive quartz (SiO₂); the photo is insufficient for a confident identification.

Dark, iron-stained rock; exact identification uncertain

Possibly a fine-grained mafic igneous rock (basalt or diabase); image alone is insufficient for a reliable species-level identification

Granite

Intrusive Igneous Rock

Sandstone

Clastic Sedimentary Rock

Sandstone

Clastic sedimentary rock (Quartz arenite)

Milky quartz with dark mineral veins

Quartz, silicon dioxide (SiO₂), likely massive vein quartz; dark veins may be chlorite, mica, iron/manganese oxides, or a sulfide mineral

Basalt with Quartz Veins

Basalt (with SiO2 veins)

Dark gray-brown stone, likely basalt or fine-grained volcanic rock

Basalt (tentative; likely plagioclase–pyroxene rock)

Sandstone

Arenite (SiO2 based)

Sandstone (with Concretion)

Arenite / Quartzose Sandstone

Likely basalt or another dark, coarse-grained igneous rock

Possibly olivine-bearing basalt (plagioclase, pyroxene, and possibly olivine); identification is uncertain from the photo

Mixed River Pebbles (including Unakite and Jasper)

Polymineralic geological specimens

Unidentified gray rock/mineral specimen

Indeterminate; possibly quartz-rich rock or a metallic sulfide-bearing specimen

Limonite (Ironstone Concretion)

Limonite: FeO(OH)·nH2O

Limonite Concretion

Limonite (FeO(OH)·nH2O) Pseudomorph