Not A Rock (Man Made Origin)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Chert (White Chert/Flint)

Microcrystalline Quartz (SiO2)

Rounded porous volcanic rock (likely scoria)

Scoria, vesicular basalt

Yellow cabochon gemstone, likely citrine or yellow glass imitation

Quartz (SiO₂), if natural citrine; visual evidence is insufficient to exclude man-made glass or resin

Polished green-and-black banded cabochon (likely malachite imitation or dyed agate)

Uncertain; possible malachite (Cu₂CO₃(OH)₂), banded agate (SiO₂), or man-made glass

Polished blue-green glassy slag or coated mineral fragment

Most likely man-made colored glass/slag; exact composition cannot be determined visually

Gossanous Sandstone (likely Terrestrial)

Arenite with Iron-Oxide inclusions

Possibly red jasper or chalcedony

Microcrystalline quartz (SiO₂), possibly iron-oxide-stained chalcedony

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

Indeterminate; likely Fe-oxide/hydroxide–stained basalt or ferruginous ironstone (goethite/limonite-rich)

Black Onyx

Chalcedony (Silicon Dioxide, SiO2)

Weathered quartz-rich rock, likely quartzite

Quartzite (mostly microcrystalline quartz, SiO₂), possibly weathered quartz vein material

Tumbled dark stone, likely basalt or slate

Basalt (fine-grained plagioclase–pyroxene rock), possibly slate/phyllite

Slate

Metamorphic Pelitic Rock

Slate

Metamorphic Pelitic Rock

Green glassy slag (often sold as “sea glass” or “green obsidian”)

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Sandstone

Arenite (primarily SiO2)

Small dark metallic-looking rock fragment

Undetermined; possibly iron oxide-rich material or a metallic mineral

Brecciated rock, likely polymict breccia

Polymict breccia; exact lithology cannot be determined from the image

Weathered granitic rock fragment

Granite, likely quartz–feldspar–biotite aggregate

Lapis Lazuli

Lapis lazuli (Complex silicate rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)

Sandstone (Quartzose)

Arenite (composed primarily of SiO2)

Artificial Rock Face (Faux Rock)

Glass Fiber Reinforced Concrete (GFRC)

Opal ring (likely precious opal)

Hydrated amorphous silica, SiO₂·nH₂O; the pictured stone may be natural opal or a lab-created/imitation opal

Milky quartz

Quartz (silicon dioxide, SiO₂)

Pink granite

Granitic rock, chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Scoria

Scoria (Vesicular Basaltic Rock)

Rounded gray pebble, likely quartzite

Quartzite (predominantly crystalline quartz, SiO₂); identification is tentative from the image

Rounded dark river pebble, likely basalt

Basalt; fine-grained mafic volcanic rock, typically plagioclase + pyroxene ± olivine

Tumbled jasper (likely yellow/brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and clay inclusions

Fossilized cylindrical shell or bone fragment

Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone

Granite

Phaneritic plutonic felsic rock

Tumbled amethyst

Amethyst, purple variety of quartz (SiO₂)

Tumbled amethyst

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

Banded Sandstone

Arenite with iron oxide banding

Likely pink granite

Granite, a coarse-grained felsic intrusive igneous rock, typically quartz + feldspar + mica

Red coral beads

Precious coral, commonly Corallium rubrum (calcium-carbonate skeleton)

Sandstone

Clastic Sedimentary Rock

Baroque cultured pearl necklace

Pearl: nacre composed mainly of aragonite (CaCO₃) and conchiolin

Fossilized Coral (Coquina/Limestone)

Cnidaria Anthozoa (Fossilized)

Emerald crystal in host rock

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Polished Stone Pendant (Identity Unclear)

Unknown (Possibly Jasper/Agate/Quartz mixture)

Gneiss

Gneiss