Not A Natural Rock

Smooth river pebble

Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert

Iridescent bismuth crystal

Bismuth (Bi), artificially crystallized and likely oxidized/coated

Bronze or iron-age decorated pottery sherd

Archaeological ceramic fragment; likely fired clay with impressed or molded decoration, not a natural rock

Goldstone (blue/black aventurine glass)

Man-made aventurine glass; silica glass containing metallic copper or other glittering inclusions

Polished black stone carving, likely soapstone/steatite

Steatite (massive talc), Mg₃Si₄O₁₀(OH)₂; exact material cannot be confirmed from the image

Unidentified dark, flat specimen

Indeterminate; image resolution is insufficient for mineral identification

Possible obsidian or slag glass

Volcanic glass, primarily SiO₂; alternatively industrial iron-rich glassy slag

Rounded river pebble (lithology unclear)

Indeterminate natural rock; no specific mineral or rock type can be identified from the image

Green sea glass (likely bottle glass)

Man-made soda-lime silicate glass; not a natural mineral

Colorless faceted gemstone (likely cubic zirconia)

Cubic zirconia, zirconium dioxide (ZrO₂); possibly synthetic quartz or glass imitation

Colorless faceted gemstone (most likely synthetic cubic zirconia)

Cubic zirconia, ZrO₂ (likely synthetic); natural alternatives include quartz or diamond

Concrete aggregate surface

Human-made cementitious composite; primarily calcium-silicate-hydrate cement with mixed silicate aggregate

Decorative gemstone-chip jewelry (likely turquoise, coral, and assorted beads)

Predominantly turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O; other pieces appear to be dyed coral or red stone, and possibly shell/metal components

Likely silicon carbide (carborundum)

Synthetic silicon carbide (SiC), likely blue-green crystalline grit

Chipped Glass/Plastic Fragment

Silicon dioxide (SiO2) for glass (amorphous) or various polymer compounds for plastic

Basalt Pebble (Beach Pebble)

Mafic Volcanic Rock (Basalt)

Weathered gray rock fragment

Likely granitic or volcanic feldspathic rock; exact identification is uncertain from the image

Weathered, iron-stained rock (likely metamorphic)

Indeterminate from photograph; possibly quartz-rich gneiss or schist

Green sea glass (likely slag glass or bottle glass)

Man-made soda-lime silicate glass; not a naturally occurring mineral

Tumbled blue stone, likely blue aventurine or dyed chalcedony

Aventurine quartz (SiO₂) or chalcedony (microcrystalline SiO₂); exact identification requires testing

Goldstone and pink quartz bead strands

Goldstone is aventurescent copper-bearing glass; pink beads are likely rose quartz (SiO₂), though dyed or glass imitations are possible

Ferruginous Slag (Iron Smelting Byproduct)

Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)

Road-surface aggregate (crushed stone)

Unidentifiable mixed lithic aggregate; likely basaltic/andesitic fragments with feldspar, quartz, and weathered rock

Obsidian-like volcanic glass (likely slag or natural obsidian)

Obsidian, primarily amorphous volcanic silica glass (approximately SiO₂); identification is uncertain from an image

Likely slag or metallic industrial byproduct

Unidentified iron-rich ferrous slag; possibly magnetite-bearing slag

Colorless faceted gemstone, likely cubic zirconia

Cubic zirconia (zirconium dioxide, ZrO₂); visual confirmation is unavailable

Possible slag or basalt fragment

Indeterminate dark mafic material; likely basalt (plagioclase–pyroxene) or industrial iron-rich slag

Gold bullion bars

Native gold (Au), likely cast or refined metal

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Faceted glass-like gemstone object

Likely synthetic glass or cubic zirconia; exact material cannot be confirmed from the image

Gemstone-set ring, likely cubic zirconia or diamond

Likely synthetic cubic zirconia (zirconium dioxide, ZrO₂); stones may alternatively be diamond (carbon, C)

ABS Plastic (Acrylonitrile Butadiene Styrene)

(C8H8)x·(C4H6)y·(C3H3N)z

Decorative opal-like turtle mosaic

Likely imitation or assembled opal material; exact stones cannot be confirmed visually

Colorless faceted gemstone, likely cubic zirconia

Cubic zirconia (synthetic zirconium dioxide, ZrO₂); possibly colorless quartz or laboratory diamond

Possible iron-rich basalt or industrial slag

Basalt, likely Fe–Mg silicate rock; exact identification is uncertain from the blurred image

Iron-rich vesicular rock, possibly slag or basalt

Uncertain; likely basaltic rock (plagioclase–pyroxene–iron oxide) or industrial iron slag

Carved greenstone figure

Likely nephrite jade (jadeite is a possible alternative), mainly amphibole-group minerals

Asphalt aggregate pavement

Bituminous asphalt concrete containing crushed stone aggregate

Polished tiger iron

Tiger iron, a banded aggregate of tiger’s-eye (quartz), red jasper, and hematite/magnetite

Sandstone

Sedimentary Clastic Rock (Quartz Arenite)

Unidentified rock fragments

Indeterminate; likely a weathered, iron-stained silicate rock

Quartz Pebble

Silicon Dioxide (SiO2)