Not A Natural Rock

Sandstone

Arenite (SiO2 based with quartz grains)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Ferruginous Sandstone

Arenite with Hematite/Limonite cement (SiO2 + Fe2O3)

Sandstone

Arenite (composed primarily of SiO2)

River Pebble (Likely Chert or Fine-Grained Sandstone/Quartzite)

Siliciclastic clast (likely Chert or Quartzarenite/Quartzite pebble)

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Sandstone

Arenite

Sandstone (Pebble)

Arenite (primarily SiO2)

Painted Pet Rock (Quartzite/Sandstone base)

Silicon Dioxide (SiO2) with anthropomorphic acrylic embellishments

Porphyry (likely Porphyritic Andesite or Basalt)

Porphyritic Igneous Rock

Granitic Gneiss

Gneiss (Metamorphic Rock)

Slate

Foliated Metamorphic Rock

Granite (Weathered)

Granitic intrusive rock

Conglomerate

Conglomerate Rock (Paraconglomerate)

Basalt

Mafic Igneous Rock

Greenschist

Greenschist facies rock

Gabbro

Plutonic mafic rock

Basalt

Mafic Igneous Rock

Slate

Slate (Metamorphic Rock)

Basalt

Mafic Igneous Rock

Gneiss

Gneissic Metamorphic Rock

Banded Gneiss

Gneiss (Metamorphic Rock)

Basalt River Stone

Basaltic Igneous Rock

Siltstone or Mudstone

Argillaceous sedimentary rock

Peridotite

Peridotite (Ultramafic Rock)

Black Tourmaline (Schorl)

NaFe3Al6(BO3)3Si6O18(OH)4

Chrome Diopside

Diopside (Magnesium Calcium Silicate) - CaMgSi2O6 + Cr

Crushed Rock (Basalt)

Basalt (Aphanitic Mafic Igneous Rock)

Basalt (Purple-tinted scoria/vesicular variety)

Extrusive mafic igneous rock (SiO2 range 45–52%)

Vesicular Basalt (Scoria)

Basalt (Vesicular)

Gastropod Fossil (Snail Steinkern)

Class Gastropoda fossil, composed of Calcium Carbonate (CaCO3)

Quartz Vein in Siltstone

SiO2 (Quartz) on clastic sedimentary matrix

Chert / Flint

Cryptocrystalline quartz (SiO2)

Labradorite

Labradorite (Ca, Na)(Al, Si)4O8

Quartzite (River Stone)

Quartzite

Granodiorite

Granodiorite (containing Quartz, Plagioclase, Orthoclase, Biotite/Hornblende)

Unakite

Unakite (altered granite)

Unakite (or Epidote-rich Granite)

Unakite (composed of Epidote {Ca2(Al, Fe)3(SiO4)3(OH)}, Pink Orthoclase Feldspar {KAlSi3O8}, and Quartz {SiO2})

Garnet Schist

Almandine Garnet Schist (Fe3Al2(SiO4)3 in Schistose matrix)

Serpentine

Antigorite, Lizardite, or Chrysotile (Mg, Fe)3Si2O5(OH)4

Basalt Pebble

Basalt

Note: Item is not a geological specimen

Homo sapiens (Dermal Appendage: Pilus)