Tektite (Impact Glass)

Quartzite (River-worn Shiner)

Quartzite (Formula: SiO2)

Amethyst (Water-Worn Pebble)

Silicon Dioxide (SiO2 with iron impurities)

Polymictic breccia, possibly volcanic breccia

Polymictic clastic breccia; likely a matrix-supported breccia containing lithic fragments, quartz, feldspar, and dark mafic minerals

Breccia (likely volcanic or impact breccia)

Polymictic breccia; clasts in a fine-grained silicate matrix, exact mineralogy indeterminate from image

Breccia (likely quartz-cemented polymict breccia)

Clastic breccia; chiefly angular quartz/feldspar or carbonate clasts in a silica- or carbonate-rich matrix

Quartzite Pebble

Quartzite (SiO2)

Carbonado (Black Diamond)

Carbonado (Polycrystalline Diamond)

Blue topaz (likely treated)

Topaz, Al₂SiO₄(F,OH)₂

Possible iron meteorite

Iron meteorite, likely an ataxite or coarse octahedrite; composition mainly Fe–Ni alloy

Iron meteorite (probable)

Fe–Ni metal, commonly kamacite and taenite

Metallic iron meteorite fragments (probable)

Iron meteorite, chiefly kamacite (α-(Fe,Ni)) with possible taenite

Iron meteorite (likely etched or weathered iron meteorite)

Fe–Ni alloy, predominantly kamacite and taenite; possible ataxite/hexahedrite or coarse octahedrite

Breccia

Polymictic volcanic breccia (likely basaltic-andesitic matrix)

Likely metallic meteorite fragment

Undetermined; possibly an iron meteorite or stony-iron meteorite

Polished boulder opal

Precious opal, hydrated amorphous silica (SiO₂·nH₂O), likely matrix/boulder opal

Rounded gravel / river pebbles

Polymictic alluvial gravel, commonly quartz-, feldspar-, and lithic-rich clasts

Raw pink chalcedony (likely pink agate/jasper)

Microcrystalline quartz, SiO₂ (chalcedony); impurities may include iron oxides and other silicates

Quartz (River Pebble)

Quartz (Silicon Dioxide - SiO2)

Muscovite

KAl2(AlSi3O10)(OH)2

Moon (lunar surface depiction)

Lunar rock; chiefly anorthosite, basalt, and breccia (plagioclase-rich CaAl2Si2O8)

Possible iron meteorite

Iron meteorite, likely kamacite–taenite alloy

Weathered iron-rich sandstone or ferruginous pebble

Quartz-rich sandstone with iron-oxide cement; exact identification requires testing

Iron meteorite (probable, possibly industrial iron slag)

Fe–Ni metallic alloy, commonly kamacite and taenite

Rhodonite

Rhodonite (MnSiO3)

Tumbled green aventurine (probable)

Quartz aggregate, predominantly SiO₂, with green fuchsite mica inclusions

Blue Topaz

Al2SiO4(F,OH)2 (Aluminum silicate fluoride hydroxide)

Likely pink granite or granitic pegmatite fragment

Granite; mainly quartz (SiO₂), feldspar, and mica

Polished orbicular jasper (likely ocean jasper)

Silicified microcrystalline quartz/chalcedony with iron-oxide and other mineral inclusions; SiO₂

Rounded gray pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene/olivine)

Tumbled carnelian/chalcedony (probable)

Microcrystalline quartz, SiO₂; orange-red variety commonly called carnelian

Rounded gray stone, likely quartz-rich granitic rock

Probable granite or granitic gneiss; mainly quartz, feldspar, and mica

Heliodor (Yellow Beryl) / Greenish-Yellow Beryl

Beryl (Be3Al2Si6O18)

Likely tumbled green mineral (possibly serpentine or aventurine)

Indeterminate; possibilities include serpentine-group minerals, nephrite, or green aventurine quartz

Likely yellow beryl or citrine gemstone in a ring

Provisional: beryl, Be₃Al₂(SiO₃)₆ (heliodor); alternative: quartz, SiO₂ (citrine)

Granite or granitic gneiss

Felsic granitoid, chiefly quartz, feldspar, and mica; possibly weakly foliated gneiss

Green jade or aventurine bead bracelet

Most likely nephrite jade (aggregated amphibole, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂) or green aventurine (quartz, SiO₂); exact identification requires testing